A manufacturing method of a thin film bulk acoustic resonator

Abstract

The present invention discloses a manufacturing method of a thin film bulk acoustic resonator, comprising: providing a first substrate; forming a cavity on the upper surface of the first substrate; forming a sacrificial layer in the cavity; sequentially forming a stacked first electrode, a piezoelectric layer, and a second electrode on the first substrate and on the sacrificial layer; at least one of the first electrode and the second electrode has an annular arched bridge, the annular arched bridge protrudes away from the piezoelectric layer, and an inner surface of the annular arched bridge encloses an annular gap; removing the sacrificial layer. In the present invention, the first electrode and / or the second electrode form an annular arched bridge structure, the annular arched bridge encloses a closed ring, and an annular gap is formed between the annular arched bridge and the surface of the plane where the piezoelectric layer is located, so that the ends of the first electrode and / or the second electrode at the boundary of the effective resonance region are in contact with the gas in the gap, thereby achieving the effect of eliminating the boundary clutter of the electrodes in the effective resonance region, and further improving the Q value of the resonator.

Description

Technical Field

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

[0002] With the continuous development of wireless communication technology, in order to meet the multi-functional requirements of various wireless communication terminals, terminal devices need to be able to transmit data using different carrier spectrums. At the same time, in order to support a sufficient data transmission rate within a limited bandwidth, strict performance requirements are also imposed on the radio frequency system. A radio frequency filter is an important part of the radio frequency system, which can filter out interference and noise outside the communication spectrum to meet the signal-to-noise ratio requirements of the radio frequency system and communication protocol. Taking a mobile phone as an example, since each frequency band requires a corresponding filter, dozens of filters may need to be set in a mobile phone.

[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, and this vibration excites a bulk acoustic wave propagating along the thickness direction of the piezoelectric thin film layer. This acoustic wave is reflected back when it reaches the interface between the upper and lower electrodes and the air, and then reflects back and forth inside the thin film to form oscillations. When the acoustic wave propagating in the piezoelectric thin film layer is exactly an odd multiple of half a wavelength, a standing wave oscillation is formed.

[0004] However, the currently fabricated cavity-type thin film bulk acoustic resonators have problems such as transverse wave loss and insufficient structural strength, resulting in the inability to further improve the quality factor (Q) and low yield, so they 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 manufacturing method of a thin film bulk acoustic resonator, which can improve the quality factor of the thin film bulk acoustic resonator and thus improve the device performance.

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

[0007] Providing a first substrate;

[0008] Forming a cavity on the upper surface of the first substrate;

[0009] Forming a sacrificial layer in the cavity;

[0010] Sequentially forming a stacked first electrode, a piezoelectric layer, and a second electrode on the first substrate and on the sacrificial layer;

[0011] At least one of the first electrode and the second electrode has an annular arched bridge, the annular arched bridge protrudes away from the piezoelectric layer, and an inner surface of the annular arched bridge encloses an annular gap;

[0012] Remove the sacrificial layer.

[0013] The beneficial effects of the present invention are as follows: The beneficial effects of the present invention are as follows: The first electrode and / or the second electrode form an annular arched bridge structure, the annular arched bridge encloses a closed ring, and an annular gap is formed between the annular arched bridge and the surface of the plane where the piezoelectric layer is located, so that the ends of the first electrode and / or the second electrode at the boundary of the effective resonance region are in contact with the gas in the gap, thereby achieving the effect of eliminating the boundary clutter of the electrodes in the effective resonance region, and further improving the Q value of the resonator.

[0014] Further, the annular arched bridge structure of the electrode serves as the boundary of the effective resonance region and surrounds the entire effective resonance region. The electrode can extend from the periphery of the effective resonance region to the first substrate, which not only improves the mechanical strength of the resonator but also reduces the impedance of the electrode.

[0015] Further, the piezoelectric layer above the cavity is not etched to form structures such as grooves and holes (compared with the case where grooves are provided in the piezoelectric layer), which can ensure the structural strength of the resonator and improve the yield of the resonator.

[0016] Further, the projections of the first electrode and the second electrode in the outer peripheral region of the annular arched bridge on the plane where the piezoelectric layer is located are staggered from each other, which can avoid the high-frequency coupling problem caused by potential floating, prevent the formation of parasitic capacitance, and is beneficial to improving the quality factor of the resonator.

[0017] Further, grooves are provided in the piezoelectric layer, so that the edge of the piezoelectric layer is exposed to the gas, which can suppress the transverse wave loss of the piezoelectric layer and improve the Q value of the resonator.

[0018] Further, the present invention adopts a bottom-up manufacturing process, and a cavity, a first electrode layer, a piezoelectric layer, and a second electrode layer are sequentially formed in the first substrate, which saves process steps and shortens the manufacturing process compared with the bonding and flipping process. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] 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 following drawings 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.

[0020] Figures 1 to 7The structural schematic diagrams corresponding to different steps of the manufacturing method of the thin film bulk acoustic wave resonator according to Embodiment 1 of the present invention are shown.

[0021] Figures 8 to 15 The structural schematic diagrams corresponding to different steps of the manufacturing method of the thin film bulk acoustic wave resonator according to Embodiment 2 of the present invention are shown.

[0022] Figures 16 to 19 The structural schematic diagrams corresponding to different steps of the manufacturing method of the thin film bulk acoustic wave resonator according to Embodiment 3 of the present invention are shown.

[0023] Figure 20 The structural schematic diagram of the resonator formed by using the manufacturing method of the thin film bulk acoustic wave resonator according to an embodiment of the present invention is shown.

[0024] Explanation of reference numerals:

[0025] 100 - First substrate; 100a - Substrate; 100b - Support layer; 101 - First electrode; 102 - Piezoelectric layer; 103 - Second electrode; 200 - Cavity; 201 - Sacrificial layer; 202 - Ring-shaped groove; 203 - Second sacrificial layer; 30 - Ring-shaped arched bridge; 31 - Ring-shaped sacrificial protrusion; 40 - Groove. Detailed description of the specific embodiments

[0026] The thin film bulk acoustic wave resonator and its manufacturing method of the present invention will be further described in detail below in conjunction with the accompanying 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 many different forms and is not limited to the specific embodiments described herein. The accompanying drawings are all in a very simplified form and use non-precise scales, only for conveniently and clearly assisting in explaining the purpose of the embodiments of the present invention.

[0027] The terms "first", "second", etc. in the specification and claims are used to distinguish between similar elements and are not necessarily used to describe a specific order or time sequence. It should be understood that, under appropriate circumstances, these terms can be replaced, for example, so that the embodiments of the present invention described herein can be operated in an order different from that described or shown herein. Similarly, if the method described herein includes a series of steps, and the order of these steps presented herein is not necessarily the only order in which these steps can be executed, and some of the described steps can be omitted and / or some other steps not described herein can be added to the method. If the components in a certain drawing are the same as those in other drawings, although these components can be easily recognized in all drawings, for the sake of clearer description of the drawings, this specification will not label the reference numerals of all the same components in each drawing.

[0028] Example 1

[0029] Embodiment 1 of the present invention provides a manufacturing method of a thin film bulk acoustic resonator. The manufacturing method includes:

[0030] S01: Provide a first substrate; form a cavity on the upper surface of the first substrate;

[0031] S02: Form a sacrificial layer in the cavity;

[0032] S03: Sequentially form a stacked first electrode, a piezoelectric layer, and a second electrode on the first substrate and on the sacrificial layer;

[0033] S04: At least one of the first electrode and the second electrode has an annular arched bridge, the annular arched bridge protrudes away from the piezoelectric layer, and the inner surface of the annular arched bridge encloses an annular gap;

[0034] S05: Remove the sacrificial layer.

[0035] It should be noted that step S0N does not represent the order of sequence.

[0036] Figures 1 to 7 are the schematic structural diagrams corresponding to the steps of the manufacturing method of the thin film bulk acoustic resonator in this embodiment. Please refer to the following Figures 1 to 7 to elaborate on the manufacturing method of the thin film bulk acoustic resonator.

[0037] Refer to Figure 1 , provide a first substrate 100. In this embodiment, the first substrate 100 is a double-layer structure, including a substrate 100a and a support layer 100b located on the substrate 100a. The material of the support layer 100b includes semiconductor material or dielectric material, and the material of the substrate 100a includes semiconductor material. In another embodiment, the first substrate 100 can also be a single-layer structure, and the material is semiconductor material. The semiconductor materials mentioned above can be silicon (Si), germanium (Ge), silicon germanium (SiGe), silicon carbide (SiC), silicon germanium carbide (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP), or other III / V compound semiconductors. The dielectric material can be silicon dioxide, silicon nitride, aluminum oxide or aluminum nitride, silicon oxynitride, silicon carbonitride.

[0038] When the first substrate 100 includes a substrate 100a and a support layer 100b located on the substrate 100a, the support layer 100b can be combined with the substrate 100a by bonding or deposition. The deposition method can be chemical vapor deposition or physical vapor deposition. The bonding methods include: covalent bonding, adhesive bonding, or fusion bonding. The support layer 100b and the substrate 100a can be bonded through a bonding layer, and the material of the bonding layer includes silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, or ethyl silicate.

[0039] Reference Figure 2 A cavity 200 is formed on the upper surface of the first substrate 100 by an etching process, and the etching process includes dry etching and wet etching. In this embodiment, the cavity 200 is formed in the support layer 100b, and the cavity 200 extends to a partial thickness of the support layer 100b, that is, the bottom of the cavity 200 exposes the support layer 100b. In another embodiment, the cavity 200 penetrates through the support layer 100b, that is, the bottom of the cavity 200 exposes the substrate 100a. The cross-sectional shape of the cavity 200 can be circular, elliptical or polygonal.

[0040] Reference Figure 3 A sacrificial layer material is deposited to cover the cavity 200 and the upper surface of the first substrate 100, and the sacrificial layer material is patterned to remove the sacrificial layer material outside the cavity 200, so that the upper surface of the sacrificial layer material in the cavity is flush with the upper surface of the first substrate 100. The sacrificial layer material in the cavity constitutes the sacrificial layer 201. The sacrificial layer material includes: phosphosilicate glass, low-temperature silicon dioxide, borophosphosilicate glass, germanium, carbon, polyimide or photoresist, and can be formed by a chemical vapor deposition process.

[0041] Reference Figure 4 In this embodiment, the first electrode does not have a ring-shaped arch structure. Forming the first electrode includes: depositing a first conductive material layer to cover the sacrificial layer 201 and the upper surface of the first substrate 100 to form the first electrode 101. The material of the first electrode 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 stack formed by the above metals. The semiconductor material is, for example, Si, Ge, SiGe, SiC, SiGeC, etc. The first conductive material layer can be formed by a physical vapor deposition process.

[0042] Reference Figure 5, a piezoelectric layer 102 is formed on the first electrode 101. 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 can be used as the material of the piezoelectric layer 102. When the material of the piezoelectric layer 102 is aluminum nitride (AlN), the piezoelectric layer 102 may further include at least one rare earth metal such as scandium (Sc), erbium (Er), yttrium (Y), and lanthanum (La). In addition, when the material of the piezoelectric layer 102 is aluminum nitride (AlN), the piezoelectric layer 102 may further include at least one transition metal such as zirconium (Zr), titanium (Ti), manganese (Mn), and hafnium (Hf). 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 102.

[0043] Continue to refer to Figure 5 , a sacrificial layer material layer is deposited and formed on the piezoelectric layer 102. The material and formation method of the sacrificial layer material layer refer to those of the sacrificial layer 201. The sacrificial layer material layer is patterned to form an annular sacrificial protrusion 31. The annular sacrificial protrusion 31 is a continuous structure that encloses a closed ring. In this embodiment, the inner boundary of the ring defines the boundary of the effective resonance region of the resonator. In this embodiment, the shape of the effective resonance region is an irregular polygon. In other embodiments, the effective resonance region may also be circular, elliptical, or an irregular shape composed of arcs and straight lines.

[0044] Refer to Figure 6 , a second electrode 103 is formed to cover the annular sacrificial protrusion 31 and the piezoelectric layer 102. The annular arched bridge 30 is formed by the second electrode 103 above the annular sacrificial protrusion 31. The material and formation method of the second electrode 103 refer to those of the first electrode 101. In this embodiment, the height of the annular sacrificial protrusion 31 is greater than the thickness of the second electrode 103 (the distance H1 between the two arrows is the height of the annular sacrificial protrusion 31, and the distance H2 between the two arrows is the thickness of the second electrode 103). In other embodiments, the height of the annular sacrificial protrusion 31 may be equal to or less than the thickness of the second electrode 103.

[0045] Refer to Figure 7, the annular sacrificial protrusion 31 is removed to form an annular void. The method of removing the annular sacrificial protrusion can be selected according to the material of the annular sacrificial protrusion. When the material of the annular sacrificial protrusion is polyimide or photoresist, it is removed by ashing. The ashing method is specifically to chemically react the oxygen released through the release holes with the annular sacrificial protrusion material at a temperature of 250 degrees Celsius to generate gaseous substances that volatilize. When the material of the annular sacrificial protrusion is low-temperature silicon dioxide, it is removed by reacting with a hydrofluoric acid solvent. The release holes are formed in the annular arch region.

[0046] In this embodiment, the boundary of the effective resonance region is defined by the inner boundary of the annular void. The minimum height of the formed annular sacrificial protrusion 31 should satisfy that resonance of the resonator cannot be achieved here, so as to achieve the purpose of defining the boundary of the effective resonance region. In this embodiment, the void height is greater than the thickness of the first electrode 101, so that the end of the first electrode 101 at the boundary of the effective resonator is completely exposed in the void, better preventing the leakage of transverse acoustic waves from the first electrode 101 and improving the quality factor of the resonator. In addition, the annular arch 30 structure of the first electrode 101 surrounds the entire effective resonance region from the outer periphery of the effective resonance region, which not only improves the mechanical strength of the resonator but also reduces the impedance of the electrode.

[0047] In this embodiment, the piezoelectric layer 102 above the cavity 200 is not etched to form structures such as grooves and holes. The piezoelectric layer 102 covers the cavity 200 and extends to the first substrate 100 outside the cavity 200, which can ensure the structural strength of the resonator and improve the yield of the resonator. In addition, the upper and lower surfaces of the piezoelectric layer 102 are both flat, so that the piezoelectric layer 102 has a good lattice orientation, improves the piezoelectric characteristics of the piezoelectric layer 102, and further improves the overall performance of the resonator.

[0048] In this embodiment, both the first electrode 101 and the second electrode 103 extend from the periphery of the effective resonance region to the first substrate 100 outside the cavity 200, ensuring the structural strength of the resonator and improving the yield. In another embodiment, it is also possible that the first electrode 101 extends from the periphery of the effective resonance region to the first substrate 100 outside the cavity 200, and the second electrode 103 is patterned so that the edge of the second electrode 103 is located within the region surrounded by the cavity 200. In still another embodiment, the first electrode 101 and the second electrode 103 can also be patterned so that the projections of the first electrode 101 and the second electrode 103 in the region outside the periphery of the annular arch 30 on the plane where the piezoelectric layer 102 is located are staggered from each other. Such a setting can avoid high-frequency coupling problems caused by potential floating, prevent the formation of parasitic capacitance, and is beneficial to improving the quality factor of the resonator.

[0049] In this embodiment, the region where the annular arch bridge 30 is located forms the boundary of the effective resonance region. In other embodiments, the boundary of the effective resonance region can be defined by other structures, and the annular arch bridge structure is arranged on the periphery of the effective resonance region.

[0050] Example 2

[0051] Figures 8 to 15 are the schematic structural diagrams corresponding to the steps of the manufacturing method of the thin film bulk acoustic wave resonator in this embodiment. Please refer to Figures 8 to 15 for an elaboration on the manufacturing method of the thin film bulk acoustic wave resonator. The difference between this embodiment and Embodiment 1 is that in this embodiment, the first electrode 101 is also formed with an annular arch bridge.

[0052] Refer to Figure 8 and Figure 9 , a first substrate 100 is provided. The first substrate 100 is a double-layer structure, including a substrate 100a and a support layer 100b located on the substrate 100a. A cavity 200 is formed on the upper surface of the first substrate 100 through an etching process, and a sacrificial layer 201 is formed in the cavity. The materials, structures, and methods involved in the above steps refer to the relevant descriptions in Embodiment 1, and will not be elaborated here.

[0053] Refer to Figure 10 , a ring-shaped groove 202 is formed in the sacrificial layer 201. The ring-shaped groove 202 can be formed by a dry etching process, and the dry etching process includes but is not limited to reactive ion etching (RIE), ion beam etching, and plasma etching. The ring-shaped groove 202 is a continuous closed structure. The included angle between the inner sidewall of the ring-shaped groove 202 and the surface of the first substrate 100 can be a right angle, an acute angle, or an arc. In this embodiment, the inner sidewall of the ring-shaped groove 202 forms the boundary of the effective resonance region, and the shape enclosed by the inner sidewall is an irregular polygon. In other embodiments, the enclosed shape can also be a circle, an ellipse, or other figures composed of straight lines and arcs. The depth of the ring-shaped groove 202 can be set with reference to the height of the annular sacrificial protrusion in Embodiment 1.

[0054] Refer to Figure 11 , the first electrode 101 is formed to cover the ring-shaped groove 202, the sacrificial layer 201, and the upper surface of the first substrate 100. The material and formation method of the first electrode 101 refer to Embodiment 1, and the formed first electrode 101 forms an annular arch bridge structure above the region where the ring-shaped groove 202 is located.

[0055] Refer to Figure 12, a sacrificial material layer is formed to cover the first electrode and fill the area where the annular arch bridge is located. The sacrificial material layer is patterned to remove the sacrificial material layer in the area outside the annular arch bridge, and the sacrificial material layer above the annular arch bridge area is retained to form the second sacrificial layer 203. The upper surface of the second sacrificial layer 203 is flush with the upper surface of the first electrode where the annular arch bridge is not formed. For the material and formation method of the sacrificial material layer in this step, refer to the material and method of forming the sacrificial material layer in the cavity in Embodiment 1.

[0056] Reference Figure 13 , a piezoelectric layer 102 is formed to cover the first electrode 101 and the second sacrificial layer 203. For the material and formation method of the piezoelectric layer 102, refer to Embodiment 1 and will not be elaborated here.

[0057] Reference Figure 14 , a sacrificial layer material layer is deposited on the piezoelectric layer 102 and patterned to form an annular sacrificial protrusion. The annular sacrificial protrusion is a continuous structure that encloses a closed ring. In this embodiment, the annular sacrificial protrusion and the annular groove are arranged oppositely. In this embodiment, the inner boundary of the annular sacrificial protrusion and the inner side wall of the annular groove overlap in the vertical direction, and both constitute the boundary of the effective resonance area of the resonator. In other embodiments, one of the boundaries can constitute the boundary of the effective resonance area, or both together can constitute the boundary of the effective resonance area, or neither of them constitutes the boundary of the effective resonance area, and the boundary of the effective resonance area is constituted by other structures. In the vertical direction, the annular sacrificial protrusion and the annular groove can be isolated from each other or partially overlap. The annular sacrificial protrusion formed in this step is the same as that in Embodiment 1. For the relevant materials, structures and formation methods, please refer to Embodiment 1.

[0058] Reference Figure 15 , the annular sacrificial protrusion and the second sacrificial layer are removed to form annular voids on both sides of the piezoelectric layer 102 respectively. The annular sacrificial protrusion and the second sacrificial layer can be made of the same material and removed by one process (at this time, through holes need to be formed in the piezoelectric layer opposite to the annular arch bridge). The removal method refers to the method of removing the annular sacrificial protrusion in Embodiment 1.

[0059] Example 3

[0060] Figures 16 to 19 are the schematic structural diagrams corresponding to the steps of the manufacturing method of the thin film bulk acoustic wave resonator in this embodiment. Next, please refer to Figures 16 to 19 to elaborate on the manufacturing method of the thin film bulk acoustic wave resonator. In this embodiment, a groove 40 is formed in the piezoelectric layer 102.

[0061] Refer to Figure 16 , in this embodiment, the steps before forming the piezoelectric layer 102 are the same as those in Embodiment 2. For the relevant steps, refer to Embodiment 2, and the drawings refer toFigures 8 to 13 After forming the piezoelectric layer 102, refer to Figure 16 , a trench 40 is formed in the piezoelectric layer 102. The trench 40 can be formed by a dry etching process. In this embodiment, the trench 40 is a closed ring and penetrates through the piezoelectric layer 102, exposing the second sacrificial layer under the piezoelectric layer 102. The inner sidewall of the trench 40 coincides with the boundary of the effective resonance region of the resonator. In other embodiments, the trench 40 can also be a discontinuous ring structure or a non-ring structure, such as only provided at a certain side boundary of the effective resonance region. At this time, the piezoelectric layer within the effective resonance region is connected to the piezoelectric layer outside the effective resonance region through the discontinuous part. In other embodiments, the trench 40 can also be provided outside the effective resonance region. Forming the trench 40 in the piezoelectric layer 102 enables the end face of the piezoelectric layer 102 and the gas in the trench 40 to form a reflection interface, effectively suppressing the leakage of transverse waves in the piezoelectric layer 102 and improving the quality factor of the resonator. The trench 40 may not penetrate through the piezoelectric layer 102. It can be understood that when the trench 40 is a closed ring and penetrates through the piezoelectric layer 102, and the sidewall of the trench 40 coincides with the boundary of the effective resonance region, the effect of suppressing transverse wave leakage is the best.

[0062] Refer to Figure 17 , a sacrificial material layer is formed to cover the piezoelectric layer 102. The sacrificial material layer fills into the trench. The material and formation method of the sacrificial material layer refer to the material and formation method of the sacrificial layer in Embodiment 1. The sacrificial material layer is patterned, and the sacrificial material layer outside the trench is removed, while the sacrificial material layer in the trench is retained, so that the upper surface of the sacrificial material layer in the trench is flush with the upper surface of the piezoelectric layer.

[0063] Refer to Figure 18 , a second electrode 103 is formed to cover the sacrificial material layer in the trench and the piezoelectric layer 102. The material and formation method of the second electrode 103 refer to the material and formation method of the first electrode in Embodiment 1.

[0064] Refer to Figure 19 , the sacrificial material layer and the annular sacrificial protrusion in the trench are removed. The sacrificial material layer and the annular sacrificial protrusion in the trench can be made of the same material and removed by one process (at this time, a release hole needs to be formed in the second electrode 103 above the trench). The removal method refers to the method of removing the annular sacrificial protrusion in Embodiment 1. In this embodiment, the trench and the annular sacrificial protrusion are arranged oppositely. In other embodiments, the two can be isolated from each other, and the sacrificial material layer in the trench and the annular sacrificial protrusion need to be removed separately.

[0065] In another embodiment, both the first electrode and the second electrode of the resonator include an annular arched bridge, and a trench is formed in the piezoelectric layer, as Figure 20 shown. The formation method can refer to Appendix Figures 9 to 13 as well as Figure 16 and Figure 17According to the relevant description, after forming a sacrificial material layer on the trench and the piezoelectric layer, the sacrificial material layer is patterned to form an annular sacrificial protrusion in the upper region of the trench. Then, a second electrode is formed to cover the annular sacrificial protrusion and the piezoelectric layer, forming a second electrode with an annular arched bridge. The sacrificial material layer in the trench and the upper and lower annular sacrificial protrusions are removed to form the structure as shown in Figure 20 described.

[0066] In the method of the above embodiments, one or both of the first electrode and the second electrode can form an annular arched bridge, and grooves can also be formed or not formed in the piezoelectric layer. The above embodiments are only examples to illustrate several situations.

[0067] The beneficial effects of the present invention are as follows: The beneficial effects of the present invention are as follows: The first electrode and / or the second electrode form an annular arched bridge structure. The annular arched bridge encloses a closed ring, and an annular gap is formed between the surface of the annular arched bridge and the plane where the piezoelectric layer is located. The ends of the first electrode and / or the second electrode at the boundary of the effective resonance region are in contact with the gas in the gap, so as to achieve the effect of eliminating the boundary clutter of the electrodes in the effective resonance region, and further improve the Q value of the resonator.

[0068] Furthermore, the annular arched bridge structure of the electrode serves as the boundary of the effective resonance region, surrounding the entire effective resonance region. The electrode can extend from the four sides of the effective resonance region to the first substrate, which not only improves the mechanical strength of the resonator but also reduces the impedance of the electrode.

[0069] Furthermore, the piezoelectric layer above the cavity is not etched to form structures such as grooves and holes (compared with the case where grooves are provided in the piezoelectric layer), which can ensure the structural strength of the resonator and improve the yield of the resonator.

[0070] Furthermore, the projections of the first electrode and the second electrode in the outer peripheral region of the annular arched bridge on the plane where the piezoelectric layer is located are staggered from each other, which can avoid high-frequency coupling problems caused by potential floating, prevent the formation of parasitic capacitance, and is beneficial to improving the quality factor of the resonator.

[0071] Furthermore, grooves are provided in the piezoelectric layer, so that the edge of the piezoelectric layer is exposed to the gas, which can suppress the transverse wave loss of the piezoelectric layer and improve the Q value of the resonator.

[0072] Furthermore, the present invention adopts a bottom-up manufacturing process, successively forming a cavity, a first electrode layer, a piezoelectric layer, and a second electrode layer in the first substrate, saving process steps and shortening the manufacturing process compared with the bonding and flipping process.

[0073] It should be noted that the various embodiments in this specification are all described in a related manner. The same or similar parts among the various embodiments can be referred to each other, and the key points of each embodiment are the differences from other embodiments.

[0074] 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 according to the above disclosure 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 Comprising: Providing a first substrate; Forming a cavity on the upper surface of the first substrate; Forming a sacrificial layer in the cavity; Sequentially forming a stacked first electrode, a piezoelectric layer, and a second electrode on the first substrate and on the sacrificial layer; At least one of the first electrode and the second electrode has an annular arched bridge, the annular arched bridge protrudes away from the piezoelectric layer, and the inner surface of the annular arched bridge encloses an annular gap; Removing the sacrificial layer; The region enclosed by the annular gap is the effective resonance region of the resonator, and the first electrode, the second electrode, and the piezoelectric layer in the effective resonance region are stacked on top of each other in a direction perpendicular to the piezoelectric layer; Forming the piezoelectric layer includes: After forming the piezoelectric layer, forming a trench in the piezoelectric layer, the trench being opposite to the annular arched bridge; The trench is a closed ring; or, The trench is intermittently arranged, and the piezoelectric layer in the effective resonance region is connected to the piezoelectric layer outside the effective resonance region through the intermittent part.

2. The manufacturing method of the thin film bulk acoustic resonator according to claim 1, characterized in that, The first electrode has an annular arched bridge structure. Forming the first electrode and the piezoelectric layer includes: Forming an annular groove in the sacrificial layer; Depositing a conductive material layer to cover the annular groove and the sacrificial layer to form a first electrode with an annular arched bridge; Forming a second sacrificial layer to cover the region where the annular arched bridge is located, the upper surface of the second sacrificial layer being flush with the upper surface of the first electrode without the annular arched bridge; Forming a piezoelectric layer to cover the first electrode and the second sacrificial layer.

3. The manufacturing method of the thin film bulk acoustic resonator according to claim 1, characterized in that, The second electrode has an annular arched bridge structure. Forming the second electrode includes: Forming a sacrificial raised material layer on the surface of the piezoelectric layer, and patterning the sacrificial raised material layer to form an annular sacrificial raised; Depositing a conductive material to cover the annular sacrificial raised and the piezoelectric layer; After removing the annular sacrificial raised, forming a second electrode with an annular arched bridge.

4. The manufacturing method of the thin film bulk acoustic resonator according to claim 1, wherein Both the first electrode and the second electrode are provided with the annular arched bridge, and the annular arched bridge of the first electrode is arranged opposite to the annular arched bridge of the second electrode.

5. The manufacturing method of the thin film bulk acoustic resonator according to claim 1, characterized in that, The first electrode extends from the periphery of the effective resonance region to the first substrate; or, both the first electrode and the second electrode extend from the periphery of the effective resonance region to the first substrate.

6. The manufacturing method of the thin film bulk acoustic resonator according to claim 1, characterized in that, When forming the first electrode and the second electrode, it further includes patterning the first electrode and the second electrode so that the projections of the first electrode and the second electrode in the direction of the first substrate are staggered from each other outside the periphery of the annular arched bridge.

7. The manufacturing method of the thin film bulk acoustic resonator according to claim 1, characterized in that The material of the first electrode or the second electrode includes one or a combination of more of molybdenum, aluminum, copper, tungsten, tantalum, platinum, ruthenium, rhodium, iridium, chromium, titanium, gold, osmium, rhenium, or palladium.

8. The manufacturing method of the thin film bulk acoustic resonator according to claim 1, characterized in that The material of the piezoelectric layer includes aluminum nitride, zinc oxide, lead zirconate titanate, lithium niobate, quartz, potassium niobate, or lithium tantalate.

9. The manufacturing method of the thin film bulk acoustic wave resonator according to claim 1, characterized in that, The material of the sacrificial layer or the annular sacrificial raised includes phosphosilicate glass, low-temperature silicon dioxide, borophosphosilicate glass, germanium, carbon, polyimide, or photoresist.

10. The manufacturing method of the thin film bulk acoustic resonator according to claim 1, characterized in that, The first substrate is a single-layer structure, and the material of the first substrate includes a semiconductor material; or, The first substrate includes a substrate and a support layer located on the substrate, the cavity is formed in the support layer, and the material of the support layer includes a semiconductor material or a dielectric material.

11. The manufacturing method of the thin film bulk acoustic resonator according to claim 10, characterized in that, The first substrate includes a substrate and a support layer located on the substrate, and the substrate and the support layer are bonded through a bonding layer.

12. The manufacturing method of the thin film bulk acoustic resonator according to claim 11, characterized in that, The material of the bonding layer includes: silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, or tetraethyl orthosilicate.

13. The manufacturing method of the thin film bulk acoustic resonator according to claim 1, characterized in that, The shape of the effective resonance region is an irregular polygon.

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