Method for manufacturing a thin film bulk acoustic resonator

Abstract

The present invention relates to a method for manufacturing a thin film bulk acoustic resonator, comprising: providing a temporary substrate; forming an etch stop layer on the temporary substrate; sequentially forming a second electrode layer, a piezoelectric layer, and a first electrode layer on the etch stop layer; etching the first electrode layer to form a first groove and a first electrode, the first groove penetrating through the first electrode; forming a support layer having a first cavity on the first electrode, the first cavity exposing the first groove and a part of the first electrode; forming a first substrate on the support layer, the first substrate covering the first cavity; removing the temporary substrate and the etch stop layer; etching the second electrode layer to form a second electrode and a second groove, the second groove penetrating through the second electrode. By forming an etch stop layer between the temporary substrate and the second electrode layer, the present invention facilitates the removal of the temporary substrate. When removing the temporary substrate, the etch stop layer is used as a barrier layer to avoid damage to the surface of the first electrode layer caused by etching, so as to prevent the instability of the electrode frequency.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor device manufacturing, and particularly to a method for manufacturing a thin film bulk acoustic resonator. Background Art

[0002] Since the analog radio frequency communication technology was developed in the early 1990s, the radio frequency front-end module has gradually become the core component of communication devices. Among all radio frequency front-end modules, the filter has become the component with the most rapid growth momentum and the greatest development prospect. With the rapid development of wireless communication technology and the increasing maturity of the 5G communication protocol, the market has put forward more stringent standards for various performance aspects of radio frequency filters. The performance of a filter is determined by the resonator units that make up the filter. In existing filters, the thin film bulk acoustic resonator (FBAR) has become one of the most suitable filters for 5G applications due to its small size, low insertion loss, large out-of-band rejection, high quality factor, high operating frequency, large power capacity, and good anti-electrostatic shock ability.

[0003] Generally, a thin film bulk acoustic resonator includes two thin film electrodes, and a piezoelectric thin film layer is provided between the two thin film electrodes. Its working principle is to utilize the piezoelectric thin film layer to generate vibrations under an alternating electric field. These vibrations excite bulk acoustic waves that propagate along the thickness direction of the piezoelectric thin film layer. These acoustic waves are reflected back at the interfaces between the upper and lower electrodes and the air, and then reflect back and forth inside the thin film to form oscillations. When the propagation of the acoustic waves in the piezoelectric thin film layer is exactly an odd multiple of half a wavelength, a standing wave oscillation is formed.

[0004] However, when removing the temporary substrate for the currently fabricated thin film bulk acoustic resonators, hydrofluoric acid is often used as an etchant, and hydrofluoric acid is extremely likely to damage the molybdenum electrode, thereby causing the frequency of the device to be unstable and resulting in a problem of poor quality factor. Moreover, its quality factor (Q) cannot be further improved, so it cannot meet the requirements of high-performance radio frequency systems. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for manufacturing a thin film bulk acoustic resonator, which can avoid electrode damage, improve the frequency stability of the device, and further improve the device performance.

[0006] To achieve the above purpose, the present invention provides a method for manufacturing a thin film bulk acoustic resonator, including:

[0007] Providing a temporary substrate;

[0008] Forming an etch stop layer on the temporary substrate;

[0009] Sequentially forming a second electrode layer, a piezoelectric layer, and a first electrode layer on the etch stop layer;

[0010] Etch the first electrode layer to form a first groove and a first electrode, the first groove penetrating the first electrode;

[0011] Form a support layer having a first cavity on the first electrode, the first cavity exposing the first groove and a part of the first electrode;

[0012] Form a first substrate on the support layer, the first substrate covering the first cavity;

[0013] Remove the temporary substrate and the etch stop layer;

[0014] Etch the second electrode layer to form a second electrode and a second groove, the second groove penetrating the second electrode.

[0015] The beneficial effects of the present invention are as follows:

[0016] By forming an etch stop layer between the temporary substrate and the second electrode layer, when removing the temporary substrate, the etch stop layer is used as a barrier layer to avoid damage to the surface of the first electrode layer caused by etching, resulting in unstable electrode frequency, thereby improving the quality factor and performance of the device; the formed first groove and second groove enclose an effective resonance region to suppress the leakage of acoustic wave energy; in addition, by flipping the structures of the first electrode, the piezoelectric layer, and the second electrode layer, the first electrode and the second electrode layer are etched respectively to form corresponding grooves, thereby avoiding etching of the piezoelectric layer during the electrode formation process, and further ensuring the integrity and flatness of the piezoelectric layer, and this method is compatible with the resonator main process, the process is simple, and the effective resonance region is effectively protected.

[0017] Further, by selecting the same material as the piezoelectric layer as the etch stop layer, it is convenient to form in the same machine tool, avoiding contamination of the surface of the etch stop layer, and further avoiding additional cleaning steps for the contaminants on the surface of the etch stop layer, saving process steps, improving production efficiency, and reducing defects.

[0018] Further, by first removing the temporary substrate through a dry etching process and then removing the etch stop layer through a wet etching process, the removal efficiency of the temporary substrate and the etch stop layer can be accelerated, the process is simple, and it is easy to execute.

[0019] Further, the wet etching rate of the wet etching process for the etch stop layer is greater than the wet etching rate for the second electrode layer, so that when etching to the second electrode layer, the etching reaction stops automatically, and the etch stop layer can be quickly removed, and damage to the surface of the second electrode layer can be avoided.

[0020] Further, the first electrode and the support layer are isolated by a dielectric layer, so as to prevent over-etching when etching to form the first cavity, and protect the surface of the first electrode located thereunder from being damaged, thereby improving the performance and reliability of the device.

[0021] Further, by etching air holes, it is convenient to balance the internal and external pressures of the first cavity. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0023] Figure 1 It is a schematic flow chart of a manufacturing method of a thin film bulk acoustic resonator provided by an embodiment of the present invention;

[0024] Figures 2-9 It is a schematic structural diagram corresponding to the corresponding steps of a manufacturing method of a thin film bulk acoustic resonator provided by the present invention.

[0025] Description of the reference numerals:

[0026] 1. Temporary substrate; 2. Isolation layer; 3. Etch stop layer; 4. First electrode; 5. Piezoelectric layer; 6. Second electrode; 6'. Second electrode layer; 7. First groove; 8. Second groove; 9. Dielectric layer; 10. Support layer; 10'. Support material layer; 11. First cavity; 12. First substrate; 13. Air hole; 14. Alignment mark. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] To solve the above problems, the present invention provides a thin film bulk acoustic resonator. By forming an etch stop layer between the temporary substrate and the second electrode layer, when removing the temporary substrate, the etch stop layer is used as a barrier layer to avoid damage to the surface of the first electrode layer caused by etching, resulting in unstable electrode frequency, protecting the device structure, and improving the quality factor and performance of the device.

[0028] The following further details the thin film bulk acoustic resonator and its manufacturing method of the present invention in conjunction with the drawings and specific embodiments. According to the following description and drawings, the advantages and features of the present invention will be clearer. However, it should be noted that the concept of the technical solution of the present invention can be implemented in various different forms and is not limited to the specific embodiments described herein. The drawings are all in a very simplified form and use non-precise scales, only for the purpose of conveniently and clearly assisting in explaining the purpose of the embodiments of the present invention.

[0029] In the specification and claims, terms such as "first", "second", etc. are used to distinguish between similar elements and are not necessarily used to describe a specific order or chronological sequence. It is to be understood that, where appropriate, these terms so used may be interchanged, for example, such that embodiments of the present invention described herein can be operated in an order different from that described or shown herein. Similarly, if the methods described herein include a series of steps, and the order of these steps presented herein is not necessarily the only order in which these steps can be performed, and some of the described steps may be omitted and / or some other steps not described herein may be added to the method. If a component in one drawing is the same as a component in other drawings, although these components can be easily recognized in all the drawings, for the sake of clarity of the description of the drawings, the present specification will not label the reference numerals of all the same components in each drawing.

[0030] Figure 1 The flowchart showing the steps of a method for manufacturing a thin film bulk acoustic resonator provided by an embodiment of the present invention is shown. Please refer to Figure 1 , the method for manufacturing a thin film bulk acoustic resonator includes:

[0031] S01: Provide a temporary substrate;

[0032] S02: Form an etch stop layer on the temporary substrate;

[0033] S03: Sequentially form a second electrode layer, a piezoelectric layer, and a first electrode layer on the etch stop layer;

[0034] S04: Etch the first electrode layer to form a first groove and a first electrode, the first groove penetrating through the first electrode;

[0035] S05: Form a support layer having a first cavity on the first electrode, the first cavity exposing the first groove and a part of the first electrode;

[0036] S06: Form a first substrate on the support layer, the first substrate covering the first cavity;

[0037] S07: Remove the temporary substrate and the etch stop layer;

[0038] S08: Etch the second electrode layer to form a second electrode and a second groove, the second groove penetrating through the second electrode.

[0039] Figures 2 to 9 The corresponding cross-sectional structure schematic diagram of the corresponding steps of a method for manufacturing a thin film bulk acoustic resonator according to this embodiment is shown. Hereinafter, the method for manufacturing a thin film bulk acoustic resonator provided by this embodiment will be described in detail with reference to Figures 2 to 9 The method for manufacturing a thin film bulk acoustic resonator provided by this embodiment will be described in detail.

[0040] Refer to Figure 2 , perform step S01 to provide a temporary substrate 1.

[0041] The temporary substrate 1 can be any suitable substrate well-known to those skilled in the art. For example, it can be at least one of the materials mentioned below: silicon (Si), germanium (Ge), silicon-germanium (SiGe), silicon carbide (SiC), silicon-germanium-carbon (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP), or other III / V compound semiconductors, and also includes multi-layer structures composed of these semiconductors, etc. Or it can be silicon-on-insulator (SOI), stacked silicon-on-insulator (SSOI), stacked silicon-germanide-on-insulator (S-SiGeOI), silicon-germanide-on-insulator (SiGeOI), and germanium-on-insulator (GeOI). Or it can also be double-sided polished wafers (DSP), or ceramic substrates such as alumina, quartz or glass substrates, etc.

[0042] After providing the temporary substrate 1, surface treatment is performed on the temporary substrate 1. The surface treatment includes: cleaning the temporary substrate 1 to remove the native oxide on the surface of the temporary substrate 1. Specifically, the temporary substrate 1 can be cleaned with chemical reagents; and then rinsed with deionized water. It should be noted that the chemical reagents can be SC1, SC2, SPM, DHF or organic solvents, etc. Among them, the SC1 solution is a mixed solution composed of NH4OH, H2O2 and H2O, the SC2 solution is a mixed solution composed of HCl, H2O2 and H2O, or it is an HCl solution, the SPM solution is a mixed solution composed of H2SO4, H2O2 and H2O, DHF is an HF solution, or it is a mixed solution composed of HF, H2O2 and H2O, or it is a mixed solution composed of HF and H2O. In addition, physical measures such as ultrasonic vibration, heating, vacuum pumping, etc. can be accompanied during the cleaning process to remove surface impurities and defects.

[0043] Reference Figures 2-3 , perform step S02 to form an etch stop layer 3 on the temporary substrate 1.

[0044] Before performing step S02, that is, before forming the etch stop layer 3 on the temporary substrate 1, an isolation layer 2 can also be formed on the temporary substrate 1 first. This facilitates separating the temporary substrate 1 from the subsequently formed second electrode layer by etching the isolation layer 2 during the subsequent stripping process, which helps to quickly strip the temporary substrate 1 and improve the process manufacturing efficiency. If no isolation layer 2 is formed between the temporary substrate 1 and the second electrode layer formed in the subsequent process, the temporary substrate 1 can be removed by mechanical grinding or other means. The materials of the isolation layer 2 include but are not limited to at least one of silicon dioxide (SiO2), silicon nitride (Si3N4), aluminum oxide (Al2O3), and aluminum nitride (AlN). The isolation layer 2 can be formed by chemical vapor deposition, magnetron sputtering, evaporation, or other methods. In this embodiment, the temporary substrate 1 is a single crystal silicon, and the material of the isolation layer 2 is silicon dioxide (SiO2).

[0045] Subsequently, step S02 is performed to form the etch stop layer 3 on the isolation layer 2, so that when removing the isolation layer 2 subsequently, the etch stop layer 3 can be used as a barrier layer to avoid damaging the corresponding electrode and ensure that the electrode frequency remains stable. The process of forming the etch stop layer 3 includes a chemical vapor deposition process or a magnetron sputtering process. The materials of the etch stop layer 3 include at least one of aluminum nitride, silicon nitride, and aluminum oxide. In this embodiment, the material of the etch stop layer 3 is the same as the material of the subsequently formed piezoelectric layer. For example, when the subsequently formed piezoelectric layer is made of aluminum nitride, the material of the etch stop layer 3 is also selected as aluminum nitride. When the etch stop layer 3 is made of the same material as the subsequently formed piezoelectric layer, it can be deposited and formed in the same device, avoiding unnecessary time waste caused by replacing the device, improving production efficiency, and avoiding device contamination caused by replacing the device to reduce surface defects and improve the growth quality of the subsequently formed piezoelectric layer.

[0046] In addition, the thickness of the formed etch stop layer 3 is 100 Å to 10,000 Å. If the etch stop layer 3 is relatively thin, the etchant for removing the isolation layer 2 is likely to damage the corresponding electrode when removing the isolation layer 2 subsequently. If the etch stop layer is relatively thick, it is not conducive to removing the etch stop layer 3 subsequently, resulting in a long removal time and low production efficiency.

[0047] Continue to refer to Figure 3 , perform step S03 to sequentially form a second electrode layer 6', a piezoelectric layer 5, and a first electrode layer on the etch stop layer 3. The piezoelectric layer 5 is located between the first electrode layer and the second electrode layer 6', and the first electrode 4 and the second electrode layer 6' are disposed opposite to each other.

[0048] Specifically, a second electrode layer 6', a piezoelectric layer 5, and a first electrode layer are sequentially formed on the isolation layer 2; the first electrode layer is patterned to form the first electrode 4. It should be noted that the first electrode layer or the second electrode layer 6' can be formed by physical vapor deposition such as magnetron sputtering and evaporation, or chemical vapor deposition; any suitable method well-known to those skilled in the art such as chemical vapor deposition, physical vapor deposition, or atomic layer deposition can be used to deposit and form the piezoelectric layer 5. By the above method, it can be ensured that the piezoelectric layer 5 has a good lattice orientation, improve the piezoelectric properties of the piezoelectric layer 5, and further improve the overall performance of the resonator. In addition, the method of patterning the first electrode layer can etch the first electrode layer by an etching process, and the etching process can be a wet etching process or a dry etching process, and preferably a dry etching process is used. The dry etching includes but is not limited to reactive ion etching (RIE), ion beam etching, plasma etching, or laser cutting.

[0049] Generally, the second electrode layer 6' and the first electrode 4 can use any suitable conductive material or semiconductor material well-known to those skilled in the art. Among them, the conductive material can be a metal material with conductive properties. For example, it is made of one of metals such as molybdenum (Mo), aluminum (Al), copper (Cu), tungsten (W), tantalum (Ta), platinum (Pt), ruthenium (Ru), rhodium (Rh), iridium (Ir), chromium (Cr), titanium (Ti), gold (Au), osmium (Os), rhenium (Re), palladium (Pd), or a laminate formed by the above metals. The semiconductor material is, for example, Si, Ge, SiGe, SiC, SiGeC, etc. The second electrode layer 6' and the first electrode 4 can be formed by physical vapor deposition such as magnetron sputtering and evaporation, or chemical vapor deposition.

[0050] The material of the piezoelectric layer 5 can use piezoelectric materials with a wurtzite crystal structure such as aluminum nitride (AlN), zinc oxide (ZnO), lead zirconate titanate (PZT), lithium niobate (LiNbO3), quartz, potassium niobate (KNbO3), or lithium tantalate (LiTaO3), and their combinations. When the piezoelectric layer 32 includes aluminum nitride (AlN), the piezoelectric layer 5 can also be doped with rare earth metals, such as at least one of scandium (Sc), erbium (Er), yttrium (Y), and lanthanum (La). In addition, when the piezoelectric layer 5 includes aluminum nitride (AlN), the piezoelectric layer 5 can also include transition metals, such as at least one of zirconium (Zr), titanium (Ti), manganese (Mn), and hafnium (Hf). In this embodiment, the second electrode layer 6' and the first electrode 4 are made of metal molybdenum (Mo), and the piezoelectric layer 5 is made of aluminum nitride (AlN).

[0051] Before forming the first groove 7, a dielectric layer 9 can also be deposited on the first electrode 4 to isolate the first electrode 4 from the subsequently formed support layer 10. When forming the first cavity by etching subsequently, the dielectric layer 9 is used as an etch stop layer to avoid damaging the surface of the first electrode 4. The material of the dielectric layer 9 includes at least one of silicon dioxide, silicon nitride, aluminum oxide, and aluminum nitride.

[0052] The materials of the dielectric layer 9 and the support layer 10 are different.

[0053] After forming the dielectric layer 9 and before forming the first groove, a registration mark 14 also needs to be formed. The registration mark 14 penetrates through the dielectric layer 9, the first electrode 4, and the piezoelectric layer 5. The registration mark 14 is composed of a dot matrix. By means of the registration mark 14, the alignment accuracy of the second electrode layer 6', the piezoelectric layer 5, the first electrode 4, and the dielectric layer 9 is improved, and problems in interlayer connection are avoided, so as to facilitate improving the etching accuracy of the subsequent first groove or second groove.

[0054] Reference Figure 4 Refer to, perform step S04 to etch the first electrode layer 4 to form the first groove 7 and the first electrode 4. The first groove 7 penetrates through the first electrode 4. Before or after forming the first groove, the first electrode layer is patterned. Specifically, it includes: coating a photoresist layer on the surface of the first electrode layer, defining a first mask pattern according to the desired pattern of the first electrode 4, then exposing it to transfer the first mask pattern structure onto the photoresist layer, then developing the photoresist layer, and using the developed photoresist layer as a mask to etch the first electrode layer by a dry etching process to form the first electrode 4, and finally removing the photoresist layer. The process of etching the first groove 7 is a dry etching process. The dry etching includes but is not limited to inductively coupled plasma (ICP) etching, reactive ion etching (RIE), ion beam etching, plasma etching, or laser cutting. In other embodiments, when etching the first electrode layer by the dry etching process to form the first electrode, the first electrode layer is also etched to form the first groove 7.

[0055] The region enclosed by the first groove 7 and the subsequently formed second groove is the effective resonance region of the resonator. By defining the effective resonance region through the first groove 7 and the subsequently formed second groove, an acoustic impedance mismatch is formed in the region where the first groove 7 and the subsequently formed second groove are located, thereby effectively suppressing sound waves. The first groove 7 and / or the subsequently formed second groove are at least partially within the range of the subsequently formed first cavity 11. The first groove 7 communicates with the first cavity 11, so that the effective resonance region is above the subsequently formed first cavity 11. When the sound wave longitudinally propagates in the effective resonance region to the air above the first cavity 11 or the second electrode layer 6', due to the acoustic impedance mismatch between the air and the electrode material, the sound wave can be reflected back into the effective resonance region, improving the effective utilization rate of the sound wave. When the formed first groove 7 and the subsequently formed second groove are all within the range of the subsequently formed first cavity 11, the effective utilization rate of the sound wave in the effective resonance region is better.

[0056] In some embodiments, since the first groove 7 and the subsequently formed second groove can define the effective resonance region, other regions of the first electrode 4, the piezoelectric layer 5, and the second electrode layer 6' do not need to be patterned otherwise, that is, the three-layer structure is flat, and the formed structure has better quality. There are no other acoustic impedance mismatch regions except the first groove 7 and the subsequently formed second groove, thereby increasing the resonance quality factor.

[0057] The depth of the first groove 7 can be determined according to the frequency of the resonator, generally 0.1 μm to 0.8 μm, and no further limitation is made in this application. In other embodiments, the formed first groove can also penetrate the piezoelectric layer 5, so that the end of the piezoelectric layer 5 is exposed in the first groove, avoiding the leakage of sound waves from the end of the piezoelectric layer 5, and effectively suppressing the leakage of sound waves.

[0058] In this embodiment, since a dielectric layer 9 is also formed on the surface of the first electrode 4, when etching to form the first groove 7, the dielectric layer 9 also needs to be etched to form the first groove 7 that penetrates the dielectric layer 9 and the first electrode 4.

[0059] Reference Figures 5-6 , perform step S05 to form a support layer 10 with a first cavity 11 on the first electrode 4. The first cavity 11 exposes the first groove 7 and part of the first electrode 4.

[0060] Specifically, the method of forming a support layer 10 with a first cavity 11 on the first electrode 4, where the first cavity 11 exposes the first groove 7 and part of the first electrode 4, includes: depositing a support material layer 10', the support material layer 10' filling the first groove and covering the first electrode 4, referring to Figure 5 ; etching the support material layer to form the first cavity 11, the support material layer outside the first cavity 11 forming the support layer 10, and the first cavity 11 exposing the first groove 7, referring toFigure 6 It should be noted that since a dielectric layer 9 is also formed on the surface of the first electrode 4, a support material layer 10' needs to be formed on the surface of the dielectric layer 9 and fill the first groove. In addition, during the formation of the first cavity 11, the dielectric layer 9 also needs to be etched so that the formed first cavity 11 penetrates through the support material layer 10' and the dielectric layer 9, that is, the first groove 7 is communicated with the first cavity 11, thereby effectively suppressing the leakage of sound waves. The method of depositing and forming the support material layer 10' can be chemical vapor deposition or physical vapor deposition.

[0061] It should be noted that the first cavity 11 is not limited to being provided in the support layer 10. In the case where the support layer 10 is not provided, the first cavity 11 can also be directly formed in the subsequently formed first substrate, and then the first substrate having the first cavity 11 is directly bonded to the first electrode 4. In addition, when forming the support material layer 10', the support material layer 10' fills the alignment marks while filling the first groove, thereby facilitating the formation of a stable support structure and enhancing the firmness of the device structure.

[0062] In this embodiment, the material of the support layer 10 can be the same as the material of the temporary substrate 1, or can be any suitable dielectric material, including but not limited to one of materials such as silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, etc. After depositing the support material layer 10' and before etching the support material layer 10', it further includes: planarizing the support material layer 10' by a chemical mechanical polishing process to ensure that the upper surface of the subsequently formed support layer 10 remains flat, thereby facilitating bonding with the subsequent first substrate. The thickness of the deposited and formed support material layer 10' is 0.5 μm to 4 μm. The support material layer 10' within this thickness range can ensure the support strength of the subsequently formed support layer 10 for the first cavity 11 and improve the reliability of the first cavity 11.

[0063] In other embodiments, the support layer 10 can be formed on the dielectric layer 9 in a bonding manner. The bonding methods include: thermocompression bonding or dry film bonding. The first electrode 4 and the support layer 10 can also be bonded through a bonding layer, and the materials of the bonding layer include silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride or ethyl silicate. In addition, the bonding layer can also adopt adhesives such as photocurable materials or thermosetting materials, such as die attach film (DAF) or dry film. The bonding methods can also include: covalent bonding, adhesive bonding or fusion bonding.

[0064] Reference Figure 7 , perform step S06 to form a first substrate 12 on the support layer 10, and the first substrate 12 covers the first cavity 11.

[0065] In this embodiment, the first substrate 12 can be directly bonded to the support layer 10; alternatively, the first substrate 12 can be combined with the support layer 10 through a bonding layer. The materials of the bonding layer include silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, or ethyl silicate. In addition, the bonding layer can also adopt adhesives such as photocurable materials or thermosetting materials, such as die attach film (DAF) or dry film, etc.

[0066] In other embodiments, when the support layer 10 is bonded to the dielectric layer 9, the formation method of the first substrate 12 and the support layer 10 can be: providing the first substrate 12; forming a support material layer on the first substrate 12; etching the support material layer to form a first cavity 11, and the process material layer outside the first cavity 11 forms the support layer 10, and the first cavity 11 extends to a partial depth of the support layer 10 or penetrates the support layer 10; bonding the support layer 10 to the dielectric layer 9.

[0067] Reference Figure 8 , perform step S07 to remove the temporary substrate and the etch stop layer 3.

[0068] The methods for removing the temporary substrate and the etch stop layer 3 include: thinning the temporary substrate; using an etching process to etch along the temporary substrate towards the second electrode layer 6' until the etch stop layer 3 is removed. In this embodiment, since an isolation layer is also formed between the temporary substrate and the second electrode layer 6', the temporary substrate can be thinned first; then a dry etching process is used to etch and remove the temporary substrate and the isolation layer. When removing the isolation layer, the etch stop layer is used as a barrier layer to avoid damaging the second electrode layer 6'; then the etch stop layer is removed by a wet etching process to facilitate subsequent etching of the second electrode layer 6' to form the second electrode. The temporary substrate, the isolation layer, and the etch stop layer are removed successively by the dry etching process and the wet etching process to accelerate the removal efficiency of the temporary substrate and the etch stop layer. The process is simple and easy to execute.

[0069] It should be noted that when using a wet etching process to remove the etch stop layer, the etchant used in the wet etching process includes at least one of phosphoric acid and hydrofluoric acid. The molar ratio of phosphoric acid to hydrofluoric acid in the solution is 1:10:60 to 1:1:1, the process temperature is 25°C to 45°C, and the etching time is 1 minute to 10 minutes. The wet etching selectivity range between the etch stop layer and the second electrode layer is 10 to 50. This kind of etchant has a relatively fast etching rate for the etch stop layer and a relatively low etching rate for the second electrode layer, so that when etching to the second electrode layer 6', the etching reaction stops automatically, and it can also quickly remove the etch stop layer and avoid damaging the surface of the second electrode layer 6'.

[0070] After removing the etch stop layer and before etching the second electrode layer 6', it further includes: planarizing the second electrode layer 6' to facilitate the removal of residues on the surface of the second electrode layer 6' after wet etching.

[0071] Continue to refer to Figure 8 , perform step S08 to etch the second electrode layer to form the second electrode 6 and the second groove 8, and the second groove 8 penetrates the second electrode 6.

[0072] It should be noted that the second groove 8 can be formed when forming the second electrode 6, or can be formed before or after forming the second electrode 6. Specifically, reference can be made to the steps of etching the first electrode layer to form the first electrode 4 and the first groove 7. The process of etching the second electrode layer to form the second electrode 6 refers to the process of etching the first electrode layer to form the first electrode 4 described above. The process of forming the second groove 8 that penetrates the second electrode 7 can refer to the formation of the first groove 4 that penetrates the first electrode described above, which will not be elaborated here.

[0073] Refer to Figure 9 , after forming the second electrode 6 and the second groove 8 that penetrates the second electrode 6, form a vent hole 13. The vent hole 13 penetrates the second electrode 6, the piezoelectric layer 5, and the first electrode 4, and the vent hole 13 communicates with the first cavity 11 to keep the pressure inside and outside the first cavity 11 balanced.

[0074] It should be noted that before or after forming the vent hole 13, part of the second electrode 6 and part of the piezoelectric layer 5 are etched away to expose part of the first electrode 4, so as to facilitate the electrical connection of the exposed first electrode 4 to the outside.

[0075] In summary, the manufacturing method of the thin film bulk acoustic resonator provided by the present invention forms an etch stop layer between the temporary substrate and the second electrode layer, so that when removing the temporary substrate, the etch stop layer is used as a barrier layer to avoid damage to the surface of the first electrode layer by etching, resulting in unstable electrode frequency, and further improving the quality factor and performance of the device; the formed first groove and second groove enclose an effective resonance region to suppress the leakage of acoustic wave energy; in addition, by flipping the structures of the first electrode, the piezoelectric layer, and the second electrode layer, the first electrode and the second electrode layer are etched respectively to form corresponding grooves, thereby avoiding etching of the piezoelectric layer during the electrode formation process, and further ensuring the integrity and flatness of the piezoelectric layer. And this method is compatible with the resonator body process, has a simple process, and effectively protects the effective resonance region.

[0076] Furthermore, by using a dry etching process to first remove the temporary substrate and then using a wet etching process to remove the etch stop layer, the removal efficiency of the temporary substrate and the etch stop layer can be accelerated, the process is simple, and it is easy to execute.

[0077] Further, the wet etching rate of the wet etching process for the etching stop layer is greater than that for the second electrode layer, so that when etching reaches the second electrode layer 6', the etching reaction stops automatically, and the etching stop layer can be quickly removed, and damage to the surface of the second electrode layer 6' can be avoided.

[0078] Further, by selecting the same material as the piezoelectric layer as the etching stop layer, it is convenient to form within the same machine, avoiding contamination of the surface of the etching stop layer, thereby avoiding additional cleaning steps for the contaminants on the surface of the etching stop layer, saving process steps, improving production efficiency, and reducing defects.

[0079] Further, the first electrode and the support layer are isolated by the dielectric layer, so as to prevent over-etching when etching to form the first cavity and protect the surface of the first electrode located thereunder from being damaged, thereby improving the device performance and reliability.

[0080] Further, by etching the air holes, it is convenient to balance the internal and external pressures of the first cavity.

[0081] It should be noted that each embodiment in this specification is described in a related manner. The same or similar parts between each embodiment can be referred to each other, and the differences between each embodiment and other embodiments are emphasized. In particular, for the structural embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the related parts can be referred to the description of the method embodiment.

[0082] The above description is only a description of the preferred embodiments of the present invention and does not limit the scope of the present invention in any way. Any changes and modifications made by those of ordinary skill in the art of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A manufacturing method of a thin film bulk acoustic wave resonator, characterized in that, Including: Providing a temporary substrate; Forming an etch stop layer on the temporary substrate; Sequentially forming a second electrode layer, a piezoelectric layer, and a first electrode layer on the etch stop layer; Etching the first electrode layer to form a first groove and a first electrode, the first groove penetrating through the first electrode; Forming a support layer having a first cavity on the first electrode, the first cavity exposing the first groove and a part of the first electrode; Forming a first substrate on the support layer, the first substrate covering the first cavity; Removing the temporary substrate and the etch stop layer; Etching the second electrode layer to form a second electrode and a second groove, the second groove penetrating through the second electrode; The method for removing the temporary substrate and the etch stop layer includes: Thinning the temporary substrate; Using an etching process to etch from the temporary substrate towards the second electrode layer until the etch stop layer is removed; The wet etching selectivity ratio range between the etch stop layer and the second electrode layer is 10 - 50; Using a wet etching process to remove the etch stop layer, the etching agent used in the wet etching process includes at least one of phosphoric acid and hydrofluoric acid, the molar ratio of phosphoric acid to hydrofluoric acid in the solution is 1:10:60 - 1:1:1, the process temperature is 25°C - 45°C, and the etching time is 1 minute - 10 minutes.

2. The manufacturing method of the thin film bulk acoustic resonator according to claim 1, characterized in that, After removing the etch stop layer and before etching the second electrode layer, it further includes: performing a planarization treatment on the second electrode layer.

3. The manufacturing method of the thin film bulk acoustic resonator according to claim 1, characterized in that, The material of the etch stop layer is the same as the material of the piezoelectric layer.

4. The manufacturing method of the thin film bulk acoustic resonator according to claim 1, characterized in that, After providing the temporary substrate, performing a surface treatment on the temporary substrate, the surface treatment includes: cleaning the temporary substrate to remove the native oxide on the surface of the temporary substrate.

5. The manufacturing method of the thin film bulk acoustic resonator according to claim 1, characterized in that, Forming the etch stop layer by chemical vapor deposition process or magnetron sputtering process.

6. The manufacturing method of the thin film bulk acoustic resonator according to claim 1, wherein The material of the etch stop layer includes at least one of aluminum nitride, silicon nitride, and aluminum oxide.

7. The manufacturing method of the thin film bulk acoustic resonator according to claim 1, characterized in that, The thickness of the formed etch stop layer is 100 Å - 10000 Å.

8. The manufacturing method of the thin film bulk acoustic resonator according to claim 1, characterized in that, Before forming the etch stop layer on the temporary substrate, forming an isolation layer on the temporary substrate; Before using the wet etching process to remove the etch stop layer, using a dry etching process to remove the isolation layer.

9. The manufacturing method of the thin film bulk acoustic resonator according to claim 8, wherein The material of the isolation layer includes at least one of silicon dioxide, silicon nitride, aluminum oxide, and aluminum nitride.

10. The manufacturing method of the thin film bulk acoustic resonator according to claim 1, characterized in that, The depth range of the formed first groove is 0.1 μm - 0.8 μm.

11. The manufacturing method of the thin film bulk acoustic resonator according to claim 1, characterized in that, The method for forming a support layer having a first cavity on the first electrode, the first cavity exposing the first groove and a part of the first electrode includes: Depositing to form a support material layer, the support material layer filling the first groove and covering the first electrode; Etching the support material layer to form a first cavity, the support material layer outside the first cavity forms a support layer, and the first cavity exposes the first groove.

12. The manufacturing method of the thin film bulk acoustic resonator according to claim 11, characterized in that, The thickness of the support material layer is 0.5 μm - 4 μm.

13. The manufacturing method of the thin film bulk acoustic resonator according to claim 11, characterized in that, After depositing the support material layer and before etching the support material layer, it further includes: performing a chemical mechanical polishing process to level the support material layer.

14. The manufacturing method of the thin film bulk acoustic resonator according to claim 1, wherein The materials of the support layer include: silicon dioxide, silicon nitride, aluminum oxide or aluminum nitride, silicon oxynitride, silicon carbonitride.

15. The manufacturing method of the thin film bulk acoustic resonator according to claim 11, characterized in that, Before forming the first groove, a dielectric layer is deposited on the first electrode; When forming the first groove, the first groove penetrates through the dielectric layer and the first electrode; When etching the support material layer, the dielectric layer is etched to form the first cavity and expose the first groove.

16. The manufacturing method of the thin film bulk acoustic resonator according to claim 15, characterized in that, The materials of the dielectric layer include at least one of silicon dioxide, silicon nitride, aluminum oxide and aluminum nitride.

17. The manufacturing method of the thin film bulk acoustic resonator according to claim 1, characterized in that, After forming the second electrode and the second groove penetrating through the second electrode, the second electrode, the piezoelectric layer and the first electrode are etched to form a ventilation hole, and the ventilation hole communicates with the first cavity.

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