A thin film bulk acoustic wave resonator and its manufacturing method and filter

Abstract

The present invention discloses a thin film bulk acoustic wave resonator and a manufacturing method and a filter thereof, wherein the acoustic wave resonator comprises: a piezoelectric laminated structure, the piezoelectric laminated structure comprises a first electrode, a piezoelectric layer and a second electrode stacked in sequence from bottom to top; at least one of the first electrode and the second electrode comprises an annular arch bridge protruding away from the surface of the piezoelectric layer, the inner surface of the arch bridge forms an annular gap, and the area surrounded by the annular gap is the effective resonance area of ​​the resonator. The present invention defines the boundary of the effective resonance area with the area where the arch bridge is located, and makes the end of the first electrode and / or the second electrode at the boundary of the effective resonance area contact with the gas in the gap, so as to achieve the effect of eliminating the boundary noise of the electrode in the effective resonance area, thereby improving the Q value of the resonator.

Description

Technical Field

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

[0002] With the continuous development of wireless communication technology, in order to meet the multifunctional requirements of various wireless communication terminals, terminal equipment needs to be able to use different carrier spectra to transmit data. At the same time, in order to support sufficient data transmission rate within a limited bandwidth, strict performance requirements are also put forward for the RF system. RF filter is an important part of the RF system, which can filter out interference and noise outside the communication spectrum to meet the signal-to-noise ratio requirements of the RF system and communication protocol. Taking mobile phones 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 film bulk acoustic wave resonator includes two film electrodes, and a piezoelectric film layer is arranged between the two film electrodes. Its working principle is to utilize the piezoelectric film layer to generate vibration under an alternating electric field. The vibration excites a bulk acoustic wave that propagates along the thickness direction of the piezoelectric film layer. The sound 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 film to form an oscillation. When the sound wave propagates in the piezoelectric film layer at an odd multiple of half the wavelength, a standing wave oscillation is formed.

[0004] However, the cavity-type thin film bulk acoustic wave resonators currently manufactured have problems such as shear wave loss and insufficient structural strength, which prevents the quality factor (Q) from being further improved and low yield rate, and therefore cannot meet the needs of high-performance RF systems. Summary of the invention

[0005] The object of the present invention is to provide a thin film bulk acoustic wave resonator and a manufacturing method thereof and a filter, which can improve the quality factor of the thin film bulk acoustic wave resonator and thus improve the device performance.

[0006] In order to achieve the above object, the present invention provides a thin film bulk acoustic wave resonator, comprising:

[0007] A piezoelectric stack structure, the piezoelectric stack structure comprising a first electrode, a piezoelectric layer, and a second electrode stacked sequentially from bottom to top;

[0008] At least one of the first electrode and the second electrode comprises an annular arch bridge protruding away from the surface of the piezoelectric layer, the inner surface of the arch bridge forms an annular gap, and the area surrounded by the annular gap is the effective resonance area of ​​the resonator.

[0009] The present invention also provides a filter, comprising at least one of the above-mentioned thin film bulk acoustic wave resonators.

[0010] The present invention also provides a method for manufacturing a thin film bulk acoustic wave resonator, comprising:

[0011] forming a first electrode, a second electrode and a piezoelectric layer, wherein the piezoelectric layer is located between the first electrode and the second electrode;

[0012] forming a sacrificial layer on the first electrode to cover a portion of the first electrode;

[0013] forming a supporting layer to cover the sacrificial layer and the periphery of the sacrificial layer;

[0014] At least one of the first electrode and the second electrode has an arch bridge, and a method for forming the electrode having the arch bridge includes:

[0015] forming an annular sacrificial protrusion; depositing a conductive material layer to cover the annular sacrificial protrusion and the surrounding area of ​​the annular sacrificial protrusion to form an electrode with an arched bridge;

[0016] The annular sacrificial protrusion is removed to form an annular gap, and the area surrounded by the annular gap is the effective resonance area of ​​the resonator;

[0017] The sacrificial layer is removed to form a cavity.

[0018] The present invention also provides a method for manufacturing a thin film bulk acoustic wave resonator, comprising:

[0019] Providing a substrate with an acoustic reflector structure, and sequentially forming a first electrode and a piezoelectric layer on the substrate;

[0020] forming an annular sacrificial protrusion on the piezoelectric layer, wherein the annular protrusion is located above the area surrounded by the acoustic reflector structure;

[0021] forming a second electrode, covering the piezoelectric layer and the annular sacrificial protrusion;

[0022] The annular sacrificial protrusion is removed to form an annular gap, and the area surrounded by the annular gap is the effective resonance area of ​​the resonator.

[0023] The beneficial effects of the present invention are as follows: the first electrode and / or the second electrode form an arch bridge structure, the arch bridge forms a closed ring, the arch bridge and the surface of the plane where the piezoelectric layer is located form a gap, the area where the arch bridge is located is used to define the boundary of the effective resonance zone, and the ends of the first electrode and / or the second electrode at the boundary of the effective resonance zone are in contact with the gas in the gap, thereby achieving the effect of eliminating the boundary noise of the electrode in the effective resonance zone, thereby improving the Q value of the resonator.

[0024] Furthermore, the piezoelectric layer above the cavity is not etched to form a groove or hole-like structure (relative to the situation where a groove is formed in the piezoelectric layer), which can ensure the structural strength of the resonator and improve the yield of the resonator.

[0025] Furthermore, the arched bridge structure of the electrode surrounds the entire effective resonance region from the periphery of the effective resonance region, thereby improving the mechanical strength of the resonator.

[0026] Furthermore, the projections of the first electrode and the second electrode in the outer peripheral area of ​​the arch bridge on the plane where the piezoelectric layer is located are staggered, which can avoid high-frequency coupling problems caused by potential floating, prevent the formation of parasitic capacitance, and help improve the quality factor of the resonator.

[0027] Furthermore, a groove is provided in the piezoelectric layer so that the edge of the piezoelectric layer is exposed to the gas, which can suppress the shear wave loss of the piezoelectric layer. When the side wall of the groove coincides with the boundary of the effective resonance area, the Q value of the resonator can be better improved.

[0028] The manufacturing method of the present invention forms a cavity by means of a sacrificial layer occupying a position, which reduces the manufacturing cost compared to forming a cavity by an etching process; by first forming an annular sacrificial protrusion and then forming an electrode, an electrode with an arch bridge structure can be conveniently formed; the piezoelectric layer is formed on a flat film layer, so that the upper surface and the lower surface of the piezoelectric layer are both flat, ensuring that the piezoelectric layer has a good lattice orientation, improving the piezoelectric characteristics of the piezoelectric layer, and thereby improving the performance of the resonator. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 A schematic structural diagram of a thin film bulk acoustic wave resonator according to embodiment 1 of the present invention is shown.

[0031] Figure 2 A schematic structural diagram of a thin film bulk acoustic wave resonator according to Embodiment 2 of the present invention is shown.

[0032] Figure 3 A schematic structural diagram of a thin film bulk acoustic wave resonator according to embodiment 3 of the present invention is shown.

[0033] Figures 4 to 8 A structural schematic diagram corresponding to different steps of a method for manufacturing a thin film bulk acoustic wave resonator according to embodiment 4 of the present invention is shown.

[0034] Figures 9 to 13 A structural schematic diagram corresponding to different steps of a method for manufacturing a thin film bulk acoustic wave resonator according to embodiment 5 of the present invention is shown.

[0035] Figures 14 to 19 Schematic diagram of the structure corresponding to different steps of the method for manufacturing a thin film bulk acoustic wave resonator according to Example 6 of the present invention.

[0036] Fig. 20 It is a schematic diagram of the structure of a thin film bulk acoustic wave resonator manufactured by using the method for manufacturing a thin film bulk acoustic wave resonator according to Example 7 of the present invention.

[0037] Description of reference numerals:

[0038] 100-first substrate; 100a-base; 100b-supporting layer; 101-first electrode; 102-piezoelectric layer; 103-second electrode; 200-cavity; 201-sacrificial layer; 310-acoustic reflector structure; 30-arch bridge; 31-annular sacrificial protrusion; 40-groove; 300-second substrate; 310-acoustic reflector structure; 1000-carrying substrate. DETAILED DESCRIPTION

[0039] The following is a further detailed description of the thin film bulk acoustic resonator and the method for making the same in combination with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer according to the following description and drawings. However, it should be noted that the concept of the technical solution of the present invention can be implemented in a variety of different forms and is not limited to the specific embodiments described herein. The drawings are all in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0040] 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 is to be understood that, where appropriate, these terms used in this way are interchangeable, for example, so that the embodiments of the invention described herein can be operated in an order other than that described or shown herein. Similarly, if the method described herein includes a series of steps, the order of these steps presented herein is not necessarily the only order in which these steps can be performed, and some of the steps described may be omitted and / or some other steps not described herein may be added to the method. If the components in a certain figure are the same as the components in other figures, although these components can be easily identified in all figures, in order to make the description of the figures clearer, this specification will not mark all the same component numbers in each figure.

[0041] Example 1

[0042] Embodiment 1 provides a thin film bulk acoustic wave resonator. Figure 1 This is a schematic diagram of the structure of a thin film bulk acoustic resonator of Example 1 of the present invention, please refer to Figure 1 , the film bulk acoustic wave resonator includes:

[0043] A piezoelectric stack structure, wherein the piezoelectric stack structure comprises a first electrode 101, a piezoelectric layer 102, and a second electrode 103 stacked in sequence from bottom to top;

[0044] At least one of the first electrode 101 and the second electrode 103 includes an annular arch bridge 30 protruding away from the surface of the piezoelectric layer 102, and the inner surface of the arch bridge 30 forms an annular gap, and the area surrounded by the annular gap is the effective resonance area of ​​the resonator.

[0045] In this embodiment, the first electrode 101 is provided with an arch bridge 30, which is a closed ring. A gap is formed between the arch bridge 30 and the lower surface of the piezoelectric layer 102, so that the area where the arch bridge 30 is located cannot achieve resonance. Therefore, the area where the arch bridge 30 is located defines the boundary of the effective resonance area of ​​the resonator. In addition, the end of the first electrode 101 at the boundary of the effective resonance area is exposed in the gap, which can reduce the transverse wave energy loss leaked from the end of the first electrode 101 and improve the quality factor of the resonator. The arch bridge structure of the electrode surrounds the entire effective resonance area from the periphery of the effective resonance area, which not only improves the mechanical strength of the resonator, but also reduces the impedance of the first electrode. In this embodiment, the effective resonance area is an irregular polygon, and any two sides of the polygon are not parallel. In other embodiments, the effective resonance area can also be a circle or an ellipse or an irregular figure composed of arcs and straight lines. The first electrode 101, the second electrode 103 and the piezoelectric layer 102 in the effective resonance area are overlapped on the surface perpendicular to the piezoelectric layer 102. In this embodiment, the second electrode 103 is not provided with an arch bridge structure. In another embodiment, the first electrode 101 may not be provided with an arch bridge, and the second electrode 103 may be provided with an arch bridge. In yet another embodiment, the first electrode and the second electrode are both provided with an arch bridge, and the two arch bridges are arranged opposite to each other. In a preferred embodiment, the projections of the inner boundaries of the two arch bridges in the direction of the surface of the first substrate overlap, which will be described in detail in Example 2. The first electrode and the second electrode both have a portion extending outside the effective resonance region, and the portion serves as an electrode connection end.

[0046] In this embodiment, the arch bridge 30 is made of the same material as the first electrode 101 and is an integral structure. In this embodiment, the piezoelectric stack structure is located on a first substrate having a cavity, and the first electrode extends from the periphery of the effective resonance region to the first substrate around the cavity 200. The second electrode 103 also extends from the effective resonance region to the first substrate 100. In other embodiments, one of the first electrode or the second electrode may also extend to the first substrate outside the cavity 200.

[0047] In this embodiment, the height of the gap formed by the arch bridge 30 is greater than the thickness of the first electrode 101 ( Figure 1 The distance H1 between the two arrows is the height of the gap, and the distance H2 between the two arrows is the thickness of the first electrode). In other embodiments, the height of the gap may be equal to the thickness of the first electrode or less than the thickness of the first electrode. The minimum height of the gap should satisfy that the resonance of the resonator cannot be achieved here. In this embodiment, the height of the gap is greater than the thickness of the first electrode, so that the end of the first electrode 101 at the boundary of the effective resonator can be completely exposed in the gap, which better prevents the transverse sound wave from leaking from the first electrode and improves the quality factor of the resonator.

[0048] In this embodiment, the piezoelectric layer above the cavity 200 is not etched to form a groove or hole-like structure, and the piezoelectric layer covers the cavity 200 and extends to the first substrate outside the cavity 200. The structural strength of the resonator can be guaranteed and the yield rate of the resonator can be improved. In addition, the upper and lower surfaces of the piezoelectric layer 102 are both planes, so that the piezoelectric layer 102 has a good lattice orientation, improves the piezoelectric properties of the piezoelectric layer, and thus improves the overall performance of the resonator.

[0049] In this embodiment, 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, thereby ensuring the structural strength of the resonator and improving the yield rate. In another embodiment, the first electrode 101 may extend from the periphery of the effective resonance region to the first substrate 100 outside the cavity 200, and the edge of the second electrode 103 is located in the area surrounded by the cavity 200. In yet another embodiment, the first electrode 101 and the second electrode 103 on the periphery of the arch bridge 30 have a non-opposite area. This arrangement can avoid the high-frequency coupling problem caused by the existence of potential floating, prevent the formation of parasitic capacitance, and help improve the quality factor of the resonator.

[0050] In this embodiment, the piezoelectric stack structure is located on a first substrate 100 having a cavity 200, and the periphery of at least one of the first electrode 101 and the second electrode 103 extends to the first substrate 100 outside the cavity 200. The figure shows that the peripheries of the first electrode 101 and the second electrode 103 both extend to the first substrate outside the cavity 200. The piezoelectric stack structure covers the cavity 200. In this embodiment, the first substrate 100 is a double-layer structure, including a base 100a and a support layer 100b, and the cavity 200 is formed in the support layer 100b. The cavity 200 extends to a portion of the thickness of the support layer 100b, that is, the bottom of the cavity 200 exposes the support layer 100b, and the material of the support layer 100b includes a semiconductor material. The material of the base 100a can be a semiconductor material or a dielectric material.

[0051] In another embodiment, the first substrate 100 includes a base 100a and a support layer 100b, the cavity 200 is formed in the support layer 100b, and the cavity 200 penetrates the support layer 100b, that is, the bottom of the cavity 200 exposes the base 100a, and the material of the support layer 100b includes a dielectric material. The material of the base 100a includes a semiconductor material.

[0052] In another embodiment, the first substrate 100 may also be a single-layer structure, and the material is a semiconductor material. The semiconductor materials mentioned above may be silicon (Si), germanium (Ge), silicon germanium (SiGe), carbon silicon (SiC), carbon germanium silicon (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP) or other III / V compound semiconductors. The dielectric material may be silicon dioxide, silicon nitride, aluminum oxide or aluminum nitride, silicon oxynitride, or silicon carbonitride.

[0053] The support layer 100b can be bonded to the substrate 100a by bonding or deposition, and the deposition method can be chemical vapor deposition or physical vapor deposition. The bonding method includes: covalent bonding, adhesive bonding or melt bonding. The support layer 100b and the substrate 100a can be bonded by a bonding layer, and the material of the bonding layer includes silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride or ethyl silicate.

[0054] The cavity 200 can be formed by a sacrificial layer process or by etching. In an optional solution, when the bottom of the cavity 200 is exposed to the support layer 100b, it is formed by a sacrificial layer process, and the specific formation method will be described in the method embodiment below. When the cavity 200 penetrates the support layer 100b, the cavity 200 is formed by etching the support layer 100b. The cross-sectional shape of the cavity 200 can be circular, elliptical or polygonal.

[0055] In another embodiment, the piezoelectric stack structure is located on a second substrate having an acoustic reflector, such as a Bragg reflector structure, which is common knowledge in the art and will not be described in detail herein.

[0056] In this embodiment, the piezoelectric stack structure covers the cavity 200, and the piezoelectric stack structure is sequentially stacked from bottom to top, including a first electrode 101, a piezoelectric layer 102, and a second electrode 103. The materials of the first electrode 101 and the second electrode 103 can be any suitable conductive material or semiconductor material known in the art, wherein the conductive material can be a metal material with conductive properties, for example, 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), etc., or made of a stack of the above metals, and the semiconductor material is, for example, Si, Ge, SiGe, SiC, SiGeC, etc. The material of the piezoelectric layer 102 can be aluminum nitride (AlN), zinc oxide (ZnO), lead zirconate titanate (PZT), lithium niobate (LiNbO3), quartz (Quartz), potassium niobate (KNbO3) or lithium tantalate (LiTaO3) and a combination thereof. When the material of the piezoelectric layer 102 is aluminum nitride (AlN), the piezoelectric layer 102 may also include a 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 also include a transition metal, such as at least one of zirconium (Zr), titanium (Ti), manganese (Mn) and hafnium (Hf).

[0057] Example 2

[0058] Embodiment 2 provides a thin film bulk acoustic wave resonator. Figure 2 Schematic diagram of the cross-sectional structure of the thin film bulk acoustic wave resonator of Example 2 of the present invention. The difference between this embodiment and Example 1 is that the piezoelectric layer in Example 1 is a complete film layer, and the piezoelectric layer in Example 2 is provided with grooves, specifically:

[0059] A groove 40 penetrating the piezoelectric layer 102 is provided along the boundary of the effective resonance zone in the piezoelectric layer 102. In the present embodiment, the groove 40 is a closed ring, and the inner side wall of the groove 40 constitutes the boundary of the effective resonance zone. The groove 40 is arranged opposite to the arch bridge 30, and the gap between the groove 40 and the arch bridge is connected. The groove 40 may not penetrate the piezoelectric layer 102. In the present embodiment, the groove 40 is a continuous ring structure. In another embodiment, the groove may also be an intermittent ring structure or a non-ring structure, such as being arranged only on one side. At this time, the piezoelectric layer in the effective resonance zone is connected to the piezoelectric layer outside the effective resonance zone through the discontinuity. In other embodiments, the groove may also be arranged on the outside of the effective resonance zone. The groove 40 is formed in the piezoelectric layer 102 so that the end face of the piezoelectric layer 102 forms a reflection interface with the gas in the groove to effectively suppress the shear wave leakage in the piezoelectric layer and improve the quality factor of the resonator. The groove may not penetrate the piezoelectric layer. It can be understood that when the groove is a closed ring and penetrates the piezoelectric layer 102, and the side wall of the groove coincides with the boundary of the effective resonance area, the effect of suppressing the shear wave leakage is the best.

[0060] The other structural features of the FBAW resonator of this embodiment are the same as those of Embodiment 1 and will not be described in detail here.

[0061] Example 3

[0062] Embodiment 3 provides a thin film bulk acoustic wave resonator, Figure 3 This is a schematic diagram of the cross-sectional structure of the thin film bulk acoustic wave resonator of Example 3 of the present invention. The difference between this embodiment and Example 2 lies in that the second electrode 103 in Example 2 does not have an arch bridge structure, while this embodiment also has an arch bridge structure on the second electrode 103. In addition, the structure of the first substrate 100 in this embodiment is different from those in Examples 1 and 2.

[0063] Specifically, in this embodiment, the second electrode 103 and the first electrode 101 are both provided with an arch bridge structure, and the two arch bridges are arranged opposite to each other, and the area surrounded by the two arch bridges is the effective resonance area of ​​the resonator. The first electrode 101 and the second electrode 103 extend from the periphery of the effective resonance area to the first substrate 100 around the cavity 200.

[0064] In this embodiment, a groove penetrating the piezoelectric layer is provided in the piezoelectric layer 102. In another embodiment, the piezoelectric layer may not be provided with a groove, and the piezoelectric layer is a complete film layer. The advantages of providing the groove are shown in Example 2, and the advantages of not providing the groove are shown in Example 1, which will not be repeated here.

[0065] In addition, the first substrate 100 in Embodiment 1 and Embodiment 2 includes a base 100a and a support layer 100b disposed on the base 100a, the cavity 200 does not penetrate the support layer 100b, and the bottom of the cavity 200 exposes the support layer 100b. In this embodiment, the first substrate 100 includes a base 100a and a support layer 100b disposed on the base 100a, the cavity 200 penetrates the support layer 100b, and the bottom of the cavity 200 exposes the upper surface of the base 100a.

[0066] Example 4

[0067] Embodiment 4 of the present invention provides a method for manufacturing a thin film bulk acoustic wave resonator, the manufacturing method comprising:

[0068] S01: forming a first electrode, a second electrode and a piezoelectric layer, wherein the piezoelectric layer is located between the first electrode and the second electrode;

[0069] S02: forming a sacrificial layer on the first electrode to cover a portion of the first electrode;

[0070] S03: forming a supporting layer to cover the sacrificial layer and the periphery of the sacrificial layer;

[0071] S04: at least one of the first electrode and the second electrode has an arched bridge, and the method for forming the electrode with the arched bridge comprises: forming an annular sacrificial protrusion; depositing a conductive material layer to cover the annular protrusion and the surrounding area of ​​the annular protrusion to form the electrode with the arched bridge;

[0072] S05: removing the annular sacrificial protrusion to form an annular gap, wherein the area surrounded by the annular gap is an effective resonance area of ​​the resonator;

[0073] S06: removing the sacrificial layer to form a cavity.

[0074] It should be noted that steps S0N do not represent a sequential order.

[0075] Figures 4 to 8 Schematic diagram of the structure corresponding to each step of the method for manufacturing the thin film bulk acoustic wave resonator of this embodiment. Figures 4 to 8 The manufacturing method of thin film bulk acoustic wave resonator is explained.

[0076] refer to Figure 4 and Figure 5 In this embodiment, the method of forming the first electrode, the second electrode and the piezoelectric layer includes:

[0077] A carrier substrate 1000 is provided, and a second electrode 103 is formed on the carrier substrate 1000 ; a piezoelectric layer 102 is formed on the second electrode 103 ; and a first electrode 101 is formed on the piezoelectric layer 102 , wherein the first electrode 101 is formed with an arch bridge structure 30 .

[0078] Specifically, refer to Figure 4 , provide a carrier substrate 1000, the carrier substrate can be a semiconductor material, such as silicon (Si), germanium (Ge), silicon germanium (SiGe), carbon silicon (SiC), carbon germanium silicon (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP) or other III / V compound semiconductors. The second electrode 103 can be formed on the carrier substrate by a physical vapor deposition process, and the material of the second electrode 103 is as shown in Example 1. The piezoelectric layer 102 can be deposited by any suitable method known to those skilled in the art, such as chemical vapor deposition, physical vapor deposition or atomic layer deposition, and the material of the piezoelectric layer 102 is as shown in Example 1.

[0079] Reference Figure 5 , a sacrificial layer material is deposited on the piezoelectric layer 102, and the sacrificial layer material includes: phosphosilicate glass, low-temperature silicon dioxide, borophosphosilicate glass, germanium, carbon, polyimide or photoresist. The patterned sacrificial layer material forms an annular sacrificial protrusion 31, and the sacrificial protrusion 31 is a continuous structure, forming a closed ring, and the boundary of the ring defines the boundary of the effective resonance area of ​​the resonator. A first electrode is formed, covering the annular sacrificial protrusion 31 and the piezoelectric layer 102, wherein the first electrode 101 above the annular sacrificial protrusion 31 forms an arch bridge 30 structure. In this embodiment, the height of the annular sacrificial protrusion 31 is greater than the thickness of the first electrode 101. In the subsequent process, the annular sacrificial protrusion 31 will be removed to form a gap. For the beneficial effects of forming the first electrode 101 with an arch bridge structure, refer to Example 1. In addition, for the setting of the height of the annular sacrificial protrusion 31, please refer to the description of the gap height in Example 1, which will not be repeated here.

[0080] Reference Figure 6 A sacrificial layer material is deposited on the first electrode 101. The selection of the sacrificial layer material is as described in the previous paragraph. The sacrificial layer material is patterned to form a sacrificial layer 201. The sacrificial layer 201 covers the arch bridge area and the surrounding area of ​​the arch bridge, exposing the first electrode 101 at the periphery.

[0081] Reference Figure 7, forming a supporting layer 100b to cover the sacrificial layer 201 and the first electrode 101. The material of the supporting layer refers to Example 1, and the supporting layer can be formed by a vapor deposition method. This embodiment also includes forming a substrate 100a on the upper surface of the supporting layer. The substrate 100a can be a semiconductor material or a dielectric material. The type of material refers to Example 1. The substrate 100a can be bonded to the supporting layer 100b by bonding, and the substrate 100a and the supporting layer 100b can be bonded by a bonding layer. The specific description refers to Example 1 and is not described here. The purpose of forming the substrate 100a is to make the bottom of the cavity formed subsequently have sufficient thickness. If the substrate 100a is not formed, the supporting layer 100b needs to be deposited thicker and the deposition process time is longer.

[0082] refer to Figure 8 , remove the carrier substrate to expose the second electrode 103. The carrier substrate can be removed by a grinding process or a wet etching process, or a release layer can be formed on the carrier substrate before forming the second electrode 103, and the carrier substrate can be peeled off by removing the release layer. The material of the release layer includes but is not limited to at least one of silicon dioxide, silicon nitride, aluminum oxide and aluminum nitride or thermal expansion tape. In one embodiment, it also includes patterning the first electrode and the second electrode so that the projections of the first electrode and the second electrode in the outer peripheral area of ​​the arch bridge are staggered on the plane where the piezoelectric layer is located. The beneficial effects of such a setting refer to the relevant description of Example 1.

[0083] The sacrificial layer is removed to form a cavity 200. The method of removing the sacrificial layer can be selected according to the material of the sacrificial layer. When the sacrificial layer material is polyimide or photoresist, it is removed by ashing. The ashing method is specifically to chemically react the oxygen in the release hole with the sacrificial layer material at a temperature of 250 degrees Celsius, and the generated gas substances are volatilized. When the sacrificial layer material is low-temperature silicon dioxide, hydrofluoric acid solvent is used to react with low-temperature silicon dioxide to remove it. The release hole can be formed in the edge area of ​​the cavity. When the material of the annular sacrificial protrusion is the same as that of the sacrificial layer, the annular sacrificial protrusion can be removed together with the sacrificial layer. The annular sacrificial protrusion and the sacrificial layer can also be removed step by step.

[0084] Example 5

[0085] Figures 9 to 13 Schematic diagram of the structure corresponding to each step of the method for manufacturing the thin film bulk acoustic wave resonator of this embodiment. Figures 9 to 13 The method for manufacturing the thin film bulk acoustic wave resonator is described. In this embodiment, the first electrode, the piezoelectric layer and the second electrode are formed in different orders.

[0086] Reference Fig. 9, provide a carrier substrate 1000, and form a first electrode 101 with an arch bridge on the carrier substrate. The materials and formation methods of the relevant film layers refer to Example 4.

[0087] Reference Fig.10 , a sacrificial material layer is deposited on the first electrode, and the sacrificial material layer is patterned to form a sacrificial layer 201. The material of the sacrificial material layer refers to that of Example 4.

[0088] Reference Fig.11 , a supporting layer 100 b is formed on the sacrificial layer 201 and the first electrode 101 , and a substrate 100 a is bonded to the supporting layer 100 b . For relevant process steps, refer to Example 4.

[0089] Reference Fig.12 , remove the carrier substrate to expose the first electrode 101 and the annular sacrificial protrusion 31 , and form a piezoelectric layer 102 on the first electrode 101 and the annular sacrificial protrusion 31 . The material and formation method of the piezoelectric layer refer to Example 4.

[0090] Reference Fig.13 , forming a second electrode 103, the material and formation method of the second electrode 103 refer to Example 4.

[0091] Example 6

[0092] Figures 14 to 19 Schematic diagram of the structure corresponding to each step of the method for manufacturing the thin film bulk acoustic wave resonator of this embodiment. Figures 14 to 19 The manufacturing method of the thin film bulk acoustic wave resonator is described. In this embodiment, the first electrode, the piezoelectric layer and the second electrode are formed in different orders, and a groove penetrating the piezoelectric layer is formed in the piezoelectric layer.

[0093] refer to Fig.14, provide a carrier substrate 1000, and form a piezoelectric layer 102 on the carrier substrate. The materials of the carrier substrate 1000 and the piezoelectric layer 102 and the method for forming the piezoelectric layer refer to Example 4. A groove 40 is formed in the piezoelectric layer 102. The groove 40 can be formed by a dry etching process. The dry etching process includes but is not limited to reactive ion etching (RIE), ion beam etching, plasma etching or laser cutting. In this embodiment, the groove 40 is a closed ring and runs through the piezoelectric layer 102. The inner side wall of the groove 40 coincides with the boundary of the effective resonance zone of the resonator. In other embodiments, the groove 40 can also be an intermittent ring structure or a non-ring structure, such as being only arranged at a certain side boundary of the effective resonance zone. In other embodiments, the groove 40 can also be arranged on the outside of the effective resonance zone. The groove 40 is formed in the piezoelectric layer 102 so that the end face of the piezoelectric layer 102 forms a reflection interface with the gas in the groove to effectively suppress the shear wave leakage in the piezoelectric layer and improve the quality factor of the resonator. The groove 40 may not penetrate the piezoelectric layer 102. It can be understood that when the groove 40 is a closed ring and penetrates the piezoelectric layer 102, and the side wall of the groove 40 coincides with the boundary of the effective resonance area, the effect of suppressing shear wave leakage is best.

[0094] refer to Fig.15 , forming a sacrificial material layer, covering the piezoelectric layer 102, the sacrificial material layer is filled into the groove, the material and formation method of the sacrificial material layer refer to Example 4, the sacrificial material layer is patterned, and an annular sacrificial protrusion 31 is formed above the groove. Regarding the structure of the annular sacrificial protrusion 31, refer to Example 4 for height.

[0095] refer to Fig.16 , forming a first electrode 101, covering the annular sacrificial protrusion 31 and the piezoelectric layer 102, wherein the first electrode 101 above the annular sacrificial protrusion 31 forms an arch bridge 30 structure. A sacrificial layer material is deposited on the first electrode 101, and the selection of the sacrificial layer material is referred to above, and the sacrificial layer material is patterned to form a sacrificial layer 201, which covers the arch bridge area and the surrounding area of ​​the arch bridge, exposing the first electrode 101 at the periphery.

[0096] refer to Fig.17 , forming a support layer 100b covering the sacrificial layer 201 and the first electrode 101, the material of the support layer is as described in Example 1, and the support layer can be formed by a vapor deposition method. This embodiment also includes forming a substrate 100a on the upper surface of the support layer, and the substrate 100a can be a semiconductor material or a dielectric material, and the type of material is as described in Example 1. The substrate 100a can be bonded to the support layer 100b by bonding.

[0097] refer to Fig.18, remove the carrier substrate to expose the piezoelectric layer 102 and the sacrificial material layer in the groove of the piezoelectric layer 102 , and the method of removing the carrier substrate is referred to Example 4. Form a sacrificial material layer to cover the piezoelectric layer 102 , and pattern the sacrificial material layer to form an annular sacrificial protrusion 31 .

[0098] refer to Fig.19 , forming a second electrode 103, covering the annular sacrificial protrusion 31 and the piezoelectric layer 102, and the formed second electrode also has an arch bridge structure. Remove the sacrificial layer, the sacrificial material in the piezoelectric layer and the two annular protrusions. In this embodiment, the two annular protrusions and the sacrificial layer material in the groove of the piezoelectric layer are connected to each other and can be removed at the same time. The arch bridge of the first electrode and the arch bridge of the second electrode formed in this embodiment are arranged oppositely, and the gaps of the two arch bridges are connected to the groove of the piezoelectric layer. The beneficial effects of forming grooves in the piezoelectric layer refer to Example 1.

[0099] The manufacturing method of the present invention forms a cavity by means of a sacrificial layer occupying a position, which reduces the manufacturing cost compared to forming a cavity by an etching process; by first forming an annular sacrificial protrusion and then forming an electrode, an electrode with an arch bridge structure can be conveniently formed; the piezoelectric layer is formed on a flat film layer, so that the upper surface and the lower surface of the piezoelectric layer are both flat, ensuring that the piezoelectric layer has a good lattice orientation, improving the piezoelectric characteristics of the piezoelectric layer, and thereby improving the performance of the resonator.

[0100] Example 7

[0101] This embodiment provides a method for manufacturing a thin film bulk acoustic wave resonator, comprising:

[0102] S01: providing a substrate with an acoustic reflector structure, and sequentially forming a first electrode and a piezoelectric layer on the substrate;

[0103] S02: forming an annular sacrificial protrusion on the piezoelectric layer, wherein the annular protrusion is located above the area surrounded by the acoustic reflector structure;

[0104] S03: forming a second electrode, covering the piezoelectric layer and the annular sacrificial protrusion;

[0105] S04: removing the annular sacrificial protrusion to form an annular gap, and the area surrounded by the annular gap is the effective resonance area of ​​the resonator.

[0106] Fig. 20 is a schematic diagram of the structure of a thin film bulk acoustic wave resonator manufactured according to the manufacturing method of the thin film bulk acoustic wave resonator of this embodiment. Fig. 20 , the manufacturing method comprises:

[0107] A substrate 300 with an acoustic reflector structure 310 is provided. The material of the substrate 300 refers to the material of the first substrate in Example 4. An acoustic reflector structure 310 is formed in the substrate 300, and the acoustic reflector structure 310 is such as a Bragg reflection structure. A first electrode 101 is formed on the upper surface of the substrate 300, and a piezoelectric layer 102 is formed on the first electrode 101. The materials and forming methods of the first electrode 101 and the piezoelectric layer 102 refer to Example 4. A sacrificial material layer is formed on the piezoelectric layer 102, and the sacrificial material layer is patterned to form an annular sacrificial protrusion. The materials and forming methods of the sacrificial material layer and the shape of the annular sacrificial protrusion refer to Example 4. A second electrode 103 is formed on the piezoelectric layer 102 and the annular sacrificial protrusion, and the first electrode above the annular sacrificial protrusion forms an arch bridge structure. The annular sacrificial protrusion is removed to form an annular gap. The method of removing the annular sacrificial protrusion refers to Example 4 and is not repeated here.

[0108] It should be noted that the various embodiments in this specification are described in a related manner, and the same and similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. For the structural embodiments, the same parts of Embodiment 2 and Embodiment 3 as those of Embodiment 1 can refer to Embodiment 1, and for the method embodiments, the same parts of Embodiment 5, Embodiment 6 and Embodiment 7 as those of Embodiment 4 can refer to Embodiment 4. The method and structural embodiments can refer to each other.

[0109] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A thin film bulk acoustic resonator, characterized in that: include: A piezoelectric stack structure, the piezoelectric stack structure comprising a first electrode, a piezoelectric layer, and a second electrode stacked sequentially from bottom to top; At least one of the first electrode and the second electrode comprises an annular arch bridge protruding in a direction away from the surface of the piezoelectric layer, the inner surface of the arch bridge forms an annular gap, and the area surrounded by the annular gap is the effective resonance area of ​​the resonator; The first electrode and the second electrode are not opposite to each other in a partial area outside the effective resonance area; A groove is provided in the piezoelectric layer, and the groove is opposite to the arch bridge; The groove penetrates through the piezoelectric layer; The groove is a continuous structure or the groove is a discontinuous structure; The sidewall of the trench coincides with the boundary of the effective resonance region.

2. The thin film bulk acoustic wave resonator according to claim 1, characterized in that: The arch bridge is made of the same material as the electrode where it is located and is an integral structure.

3. The thin film bulk acoustic wave resonator according to claim 1, characterized in that: The first electrode and the second electrode each have a portion extending outside the effective resonance region, and the portion serves as an electrode connection end.

4. The thin film bulk acoustic wave resonator according to claim 1, characterized in that: The piezoelectric stack structure is located on a first substrate having a cavity, and the periphery of at least one of the first electrode and the second electrode extends to the first substrate outside the cavity.

5. The thin film bulk acoustic resonator according to claim 4, characterized in that: The piezoelectric layer covers the cavity and extends out of the cavity.

6. The thin film bulk acoustic wave resonator according to claim 1, characterized in that: The shape of the effective resonance area is an irregular polygon.

7. The thin film bulk acoustic resonator according to claim 1, characterized in that The piezoelectric stack structure is located on a second substrate having an acoustic reflector.

8. The thin film bulk acoustic wave resonator according to claim 4, characterized in that: The first substrate includes a base and a supporting layer, the supporting layer and the piezoelectric stacked structure are stacked on the base in sequence, and the cavity is arranged in the supporting layer; or the first substrate is a semiconductor substrate, and the cavity is located in the upper surface cavity of the semiconductor substrate.

9. The thin film bulk acoustic resonator according to claim 8, characterized in that: The cavity penetrates the supporting layer; or, the cavity extends to a partial thickness of the supporting layer.

10. The thin film bulk acoustic wave resonator according to claim 9, characterized in that: The material of the substrate includes a semiconductor material, and the material of the support layer includes a dielectric material.

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

12. The thin film bulk acoustic wave 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.

13. A filter comprising at least one thin film bulk acoustic resonator according to any one of claims 1 to 12.

14. A method for manufacturing a thin film bulk acoustic wave resonator, characterized in that: include: forming a first electrode, a second electrode and a piezoelectric layer, wherein the piezoelectric layer is located between the first electrode and the second electrode; forming a sacrificial layer on the first electrode to cover a portion of the first electrode; forming a supporting layer to cover the sacrificial layer and the periphery of the sacrificial layer; At least one of the first electrode and the second electrode has an arch bridge, and a method for forming the electrode having the arch bridge includes: forming an annular sacrificial protrusion; depositing a conductive material layer to cover the annular sacrificial protrusion and the surrounding area of ​​the annular sacrificial protrusion to form an electrode with an arched bridge; The annular sacrificial protrusion is removed to form an annular gap, and the area surrounded by the annular gap is the effective resonance area of ​​the resonator; removing the sacrificial layer to form a cavity; After forming the piezoelectric layer, etching the piezoelectric layer to form a groove penetrating the piezoelectric layer, wherein the groove is opposite to the arch bridge; The groove is a closed ring, or The grooves are arranged discontinuously, and the piezoelectric layer in the effective resonance region is connected to the piezoelectric layer outside the effective resonance region through the discontinuities; The groove is connected with the gap; The first electrode and the second electrode extend from the effective resonance region to the periphery of the cavity.

15. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 14, characterized in that: The method of forming the first electrode, the second electrode and the piezoelectric layer comprises: Providing a carrier substrate; forming a first electrode on the carrier substrate; After forming the support layer, removing the carrier substrate, and forming a piezoelectric layer on the first electrode; forming a second electrode on the piezoelectric layer; or, Providing a carrier substrate; forming a piezoelectric layer on the carrier substrate; forming a first electrode on the piezoelectric layer; After forming the support layer, removing the carrier substrate, and forming a second electrode on the piezoelectric layer; or Providing a carrier substrate; forming a second electrode on the carrier substrate; forming a piezoelectric layer on the second electrode; forming a first electrode on the piezoelectric layer; After forming the support layer, the carrier substrate is removed.

16. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 14, characterized in that: The forming of the first electrode and the second electrode further includes patterning the first electrode and the second electrode so that the projections of the first electrode and the second electrode are staggered at the periphery of the cavity.

17. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 14, characterized in that: The material of the annular sacrificial protrusion includes phosphosilicate glass, low-temperature silicon dioxide, borophosphosilicate glass, germanium, carbon, polyimide or photoresist.

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