WO2022057769A1

WO2022057769A1 - Thin-film bulk acoustic wave resonator and method for manufacture thereof and filter

Info

Publication number: WO2022057769A1
Application number: PCT/CN2021/118000
Authority: WO
Inventors: 黄河
Original assignee: 中芯集成电路（宁波）有限公司上海分公司
Priority date: 2020-09-21
Filing date: 2021-09-13
Publication date: 2022-03-24
Also published as: CN114257197A

Abstract

Disclosed are a thin-film bulk acoustic wave resonator and method for manufacture thereof and filter, the acoustic wave resonator comprising: a piezoelectric stack structure, said piezoelectric stack structure comprising a first electrode, a piezoelectric layer, and a second electrode, stacked in sequence from bottom to top; at least one of said first electrode and said second electrode comprises an annular arched bridge projecting in the direction away from the surface of said piezoelectric layer, the inner surface of said arched bridge enclosing an annular void, the area enclosed by said annular void being the effective resonant region of the resonator. In the present invention, the boundary of the effective resonant region is defined by the area where the arched bridge is located, and the ends of the first electrode and/or the second electrode at the boundary of the effective resonant region are caused to be in contact with gas in the void, thus the effect of eliminating the boundary clutter of the electrode in the effective resonant region is achieved, and the Q value of the resonator is increased.

Description

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

technical field

The invention relates to the field of semiconductor device manufacturing, in particular to a thin-film bulk acoustic wave resonator, a manufacturing method thereof, and a filter.

Background technique

With the continuous development of wireless communication technology, in order to meet the multi-functional requirements of various wireless communication terminals, the terminal equipment needs to be able to transmit data using different carrier frequency spectrums. The system also imposes stringent performance requirements. The radio frequency filter is an important part of the radio frequency system, which can filter out the interference and noise outside the communication spectrum to meet the requirements of the radio frequency system and the communication protocol for the signal-to-noise ratio. Taking a mobile phone as an example, since each frequency band needs a corresponding filter, dozens of filters may need to be set in a mobile phone.

Generally, a thin-film bulk acoustic wave resonator includes two thin-film electrodes, and a piezoelectric thin-film layer is arranged between the two thin-film electrodes. The bulk acoustic wave propagating in the thickness direction of the electric film layer is transmitted to the interface between the upper and lower electrodes and the air and is reflected back, and then reflected back and forth inside the film to form an oscillation. Standing wave oscillations are formed when a sound wave propagates in a piezoelectric film layer that is exactly an odd multiple of a half-wavelength.

technical problem

However, the cavity-type thin-film bulk acoustic wave resonators currently produced have problems such as shear wave loss, insufficient structural strength, so that the quality factor (Q) cannot be further improved, and the yield is low, so they cannot meet the needs of high-performance RF systems.

technical solutions

The purpose of the present invention is to provide a thin film bulk acoustic wave resonator, a manufacturing method and a filter thereof, which can improve the quality factor of the thin film bulk acoustic wave resonator, thereby improving the device performance.

In order to achieve the above object, the present invention provides a thin film bulk acoustic resonator, comprising: a piezoelectric laminated structure, wherein the piezoelectric laminated structure includes 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 arched bridge protruding away from the surface of the piezoelectric layer, the inner surface of the arched bridge forms an annular gap, the annular The area enclosed by the gap is the effective resonance area of the resonator.

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

The present invention also provides a method for manufacturing a thin film bulk acoustic resonator, comprising: 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, covering part of the first electrode; forming a support layer, covering the sacrificial layer and the outer periphery of the sacrificial layer; the first electrode, the second electrode at least wherein One of the electrodes has an arched bridge, and a method for forming an electrode with an arched bridge includes: forming an annular sacrificial protrusion; The electrode of the arch bridge; the annular sacrificial protrusion is removed to form an annular space, and the area enclosed by the annular space is an effective resonance area of the resonator; the sacrificial layer is removed to form a cavity.

The present invention also provides a method for manufacturing a thin-film bulk acoustic resonator, comprising: providing a substrate with an acoustic mirror structure, forming a first electrode and a piezoelectric layer in sequence on the substrate; forming a ring-shaped layer on the piezoelectric layer a sacrificial protrusion, the annular protrusion is located above the area surrounded by the acoustic mirror structure; a second electrode is formed to cover the piezoelectric layer and the annular sacrificial protrusion; the annular sacrificial protrusion is removed to form an annular space , the area enclosed by the annular gap is the effective resonance area of the resonator.

beneficial effect

The beneficial effects of the present invention are as follows: the first electrode and/or the second electrode form an arched bridge structure, the arched bridge is enclosed in a closed ring, and the arched bridge forms a gap with the surface of the plane where the piezoelectric layer is located, and the arched bridge is used to form a gap. The area of the effective resonance area defines the boundary of the effective resonance area, and the end of the first electrode and/or the second electrode at the boundary of the effective resonance area is 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 area, In turn, the Q value of the resonator is increased.

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

Further, the arch bridge structure of the electrode surrounds the entire effective resonance region from the outer periphery of the effective resonance region, thereby improving the mechanical strength of the resonator.

Further, 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 the problem of high-frequency coupling caused by the existence of potential floating, prevent the formation of parasitic capacitance, and help improve resonance. device quality factor.

Further, 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. The Q value of the boosting resonator.

In the manufacturing method of the present invention, the cavity is formed by the sacrificial layer occupying the space, which reduces the manufacturing cost compared with forming the cavity through an etching process; The electrode of the bridge structure; the piezoelectric layer is formed on the flat film layer, so that the upper surface and the lower surface of the piezoelectric layer are flat, so as to ensure that the piezoelectric layer has a good lattice orientation and improve the piezoelectric layer of the piezoelectric layer. characteristics, thereby improving the performance of the resonator.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts.

FIG. 1 shows a schematic structural diagram of a thin film bulk acoustic wave resonator according to Embodiment 1 of the present invention.

FIG. 2 shows a schematic structural diagram of a thin film bulk acoustic wave resonator according to Embodiment 2 of the present invention.

FIG. 3 shows a schematic structural diagram of a thin film bulk acoustic wave resonator according to Embodiment 3 of the present invention.

FIG. 4 to FIG. 8 are schematic structural diagrams corresponding to different steps of the manufacturing method of the thin-film bulk acoustic resonator according to Embodiment 4 of the present invention.

9 to 13 are schematic structural diagrams corresponding to different steps of the manufacturing method of the thin-film bulk acoustic resonator according to Embodiment 5 of the present invention.

14 to 19 are schematic structural diagrams corresponding to different steps of the manufacturing method of the thin film bulk acoustic resonator according to Embodiment 6 of the present invention.

FIG. 20 is a schematic structural diagram of a thin-film bulk acoustic resonator manufactured by the method for manufacturing a thin-film bulk acoustic resonator according to Embodiment 7 of the present invention.

100-first substrate; 100a-base; 100b-support layer; 101-first electrode; 102-piezoelectric layer; 103-second electrode; 200-cavity; 201-sacrificial layer; 310 - acoustic mirror structure; 30 - arched bridge; 31 - annular sacrificial protrusion; 40 - groove; 300 - second substrate; 310 - acoustic mirror structure; 1000 - carrier substrate.

Embodiments of the present invention

The thin film bulk acoustic wave resonator and the manufacturing method thereof of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer from the following description and accompanying drawings. However, it should be noted that the concept of the technical solution of the present invention can be implemented in various forms, and is not limited to the specific implementation described here. example. The accompanying drawings are all in a very simplified form and in an inaccurate scale, and are only used to facilitate and clearly assist the purpose of explaining the embodiments of the present invention.

The terms "first," "second," and the like, in the specification and claims are used to distinguish between similar elements, and are not necessarily used to describe a particular order or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances, eg, to enable the embodiments of the invention described herein to operate in other sequences than described or illustrated herein. Similarly, if a method described herein includes a series of steps, the order of the steps presented herein is not necessarily the only order in which the steps may be performed, and some of the steps described may be omitted and/or some not described herein Additional steps can be added to this method. If the components in a certain drawing are the same as the components in other drawings, although these components can be easily identified in all the drawings, in order to make the description of the drawings clearer, this specification will not refer to all the same components. Numbers are attached to each figure.

Example 1

Embodiment 1 provides a thin-film bulk acoustic resonator. FIG. 1 is a schematic structural diagram of a thin-film bulk acoustic resonator according to example 1 of the present invention. Please refer to FIG. 1. The thin-film bulk acoustic resonator includes: a piezoelectric laminated structure, The piezoelectric laminated structure includes a first electrode 101, a piezoelectric layer 102 and a second electrode 103 stacked in sequence from bottom to top; at least one of the first electrode 101 and the second electrode 103 includes a The piezoelectric layer 102 has an annular arched bridge 30 with a convex surface. The inner surface of the arched bridge 30 forms an annular space, and the area enclosed by the annular space is an effective resonance area of the resonator.

In this embodiment, the first electrode 101 is provided with an arched bridge 30, the arched bridge 30 is a closed ring, and a gap is formed between the arched bridge 30 and the lower surface of the piezoelectric layer 102, so that the area where the arched bridge 30 is located Resonance cannot be achieved, so the area in which the arched bridge 30 is located defines the boundaries of the effective resonance region of the resonator. In addition, the end of the first electrode 101 at the boundary of the effective resonance region is exposed in the gap, which can reduce the loss of shear wave energy leaking 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 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 first electrode. In this embodiment, the effective resonance region is an irregular polygon, and any two sides of the polygon are not parallel. In other embodiments, the effective resonance region may also be a circle or an ellipse, or an irregular pattern formed by arcs and straight lines. The first electrode 101 , the second electrode 103 and the piezoelectric layer 102 in the effective resonance region are stacked on each other perpendicular to the surface of 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, both the first electrode and the second electrode are provided with arch bridges, and at this time, the two arch bridges are arranged opposite to each other. In a preferred solution, the inner boundaries of the two arch bridges are in the direction of the surface of the first substrate. The projection coincidence of , will be described in detail in Example 2. Both the first electrode and the second electrode have a portion extending outside the effective resonance region, and the portion serves as an electrode connection terminal.

In this embodiment, the arched bridge 30 and the first electrode 101 are made of the same material and have an integral structure. In this embodiment, the piezoelectric stacked structure is located on a first substrate having a cavity, and the first electrodes extend 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 onto 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 .

In this embodiment, the height of the gap formed by the arched bridge 30 is greater than the thickness of the first electrode 101 (the distance H1 between the two arrows in FIG. 1 is the height of the gap, and the distance H2 between the two arrows is the first electrode thickness), in other embodiments, the height of the void may be equal to 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 to the gap. In the process, the leakage of transverse acoustic waves from the first electrode is better prevented, and the quality factor of the resonator is improved.

In this embodiment, the piezoelectric layer above the cavity 200 is not etched to form structures such as grooves or holes. 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 ensured, and the yield of the resonator can be improved. In addition, the upper surface and the lower surface of the piezoelectric layer 102 are both flat, so that the piezoelectric layer 102 has a better lattice orientation, which improves the piezoelectric properties of the piezoelectric layer, thereby improving the overall performance of the resonator.

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 around the cavity 200, which ensures the structural strength of the resonator and improves the yield. In another embodiment, the first electrode 101 may also extend from the periphery of the effective resonant region to the first substrate 100 at the periphery of the cavity 200 , and the edge of the second electrode 103 is located in the area surrounded by the cavity 200 . within the area. In yet another embodiment, the first electrode 101 and the second electrode 103 on the periphery of the arched bridge 30 have non-opposing regions. This arrangement can avoid the problem of high-frequency coupling caused by the existence of floating potential, prevent the formation of parasitic capacitance, and is beneficial to improve the quality factor of the resonator.

In this embodiment, the piezoelectric laminated structure is located on the first substrate 100 having the cavity 200 , and the periphery of at least one of the first electrode 101 and the second electrode 103 extends to the first substrate outside the cavity 200 . on a substrate 100 . The figure shows that the outer 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, the cavity 200 is formed in the support layer 100b, and the cavity 200 extends to a part of the thickness of the support layer 100b, that is, the cavity The bottom of 200 exposes the support layer 100b, and the material of the support layer 100b includes a semiconductor material. The material of the substrate 100a may be a semiconductor material or a dielectric material.

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 through the support layer 100b, that is, the bottom of the cavity 200 exposes the base 100a , the material of the support layer 100b includes a dielectric material. The material of the substrate 100a includes semiconductor material.

In yet another embodiment, the first substrate 100 may also have a single-layer structure, and the material is a semiconductor material. The semiconductor materials mentioned above can be silicon (Si), germanium (Ge), silicon germanium (SiGe), silicon carbon (SiC), silicon germanium carbon (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, silicon carbonitride.

The support layer 100b may be combined with the substrate 100a by bonding or deposition, and the deposition may 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.

The cavity 200 may be formed by a sacrificial layer process or by etching. In an alternative solution, when the support layer 100b is exposed at the bottom of the cavity 200, it is formed by a sacrificial layer process, and the specific formation method will be described in the following method embodiments. When the cavity 200 penetrates through the support layer 100b, the cavity 200 is formed by etching the support layer 100b. The cross-sectional shape of the cavity 200 may be a circle, an ellipse or a polygon.

In another embodiment, the piezoelectric stack is on a second substrate having an acoustic mirror. The acoustic mirror is such as a Bragg reflection structure, and the Bragg reflection structure is a common knowledge in the art, and will not be described in detail here.

In this embodiment, the piezoelectric stack structure covers the cavity 200 , and the piezoelectric stack structure includes a first electrode 101 , a piezoelectric layer 102 and a second electrode 103 that are stacked in sequence from bottom to top. The material 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, 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) and other metals, or a laminate of the above metals, and the semiconductor material is, for example, Si, Ge, SiGe, SiC, SiGeC et al. The piezoelectric layer 102 can be made of aluminum nitride (AlN), zinc oxide (ZnO), lead zirconate titanate (PZT), lithium niobate (LiNbO ₃ ), quartz (Quartz), potassium niobate (KNbO ₃ ) or Piezoelectric materials having a wurtzite crystal structure, such as lithium tantalate (LiTaO ₃ ), and combinations thereof. When the piezoelectric layer 102 is made of aluminum nitride (AlN), the piezoelectric layer 102 may further include a rare earth metal, such as at least one of 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 transition metals such as zirconium (Zr), titanium (Ti), manganese (Mn), and hafnium (Hf). at least one.

Example 2

Embodiment 2 provides a thin film bulk acoustic resonator. FIG. 2 is a schematic cross-sectional structure diagram of the thin film bulk acoustic wave resonator according to Embodiment 2 of the present invention. The difference between this embodiment and Embodiment 1 is that the piezoelectric The layer is a complete film layer. The piezoelectric layer in Example 2 is provided with a groove, specifically: the piezoelectric layer 102 is provided with a groove 40 penetrating the piezoelectric layer 102 at the boundary of the effective resonance region. In an example, the groove 40 is a closed ring, the inner sidewall of the groove 40 constitutes the boundary of the effective resonance area, the groove 40 is disposed opposite the arch bridge 30, and the gap between the groove 40 and the arch bridge communicates. The trench 40 may not penetrate through the piezoelectric layer 102 . In this embodiment, the groove 40 is a continuous annular structure. In another embodiment, the groove can also be an intermittent annular structure or a non-annular structure, such as being provided only on one side. At this time, the piezoelectric layer in the effective resonance area is connected with the piezoelectric layer outside the effective resonance area through the discontinuity. In other embodiments, the trenches may also be provided outside the effective resonance region. A trench 40 is formed in the piezoelectric layer 102, so that the end face of the piezoelectric layer 102 and the gas in the trench form a reflection interface, so as to effectively suppress the leakage of transverse waves in the piezoelectric layer and improve the quality factor of the resonator. The trench may also not penetrate the piezoelectric layer. It can be understood that when the trench is a closed ring and penetrates through the piezoelectric layer 102 , and the sidewall of the trench coincides with the boundary of the effective resonance region, the effect of suppressing the shear wave leakage is the best.

Other structural features of the thin-film bulk acoustic wave resonator in this embodiment are the same as those in Embodiment 1, and will not be repeated here.

Example 3

Embodiment 3 provides a thin-film bulk acoustic resonator. FIG. 3 is a schematic cross-sectional structure diagram of the thin-film bulk acoustic resonator in Embodiment 3 of the present invention. The difference between this embodiment and Embodiment 2 is that the second The electrode 103 is not provided with an arched bridge structure, and the second electrode 103 is also provided with an arched bridge structure in this embodiment. In addition, the structure of the first substrate 100 in this embodiment is different from that of Embodiment 1 and Embodiment 2.

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

In this embodiment, the piezoelectric layer 102 is provided with a groove penetrating the piezoelectric layer. In another embodiment, the piezoelectric layer may not be provided with a groove and is a complete film layer. Refer to Embodiment 2 for the benefits of providing grooves, and refer to Embodiment 1 for the benefits of not providing grooves, which will not be repeated here.

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 through 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 through the support layer 100b, and the bottom of the cavity 200 exposes the upper surface of the base 100a.

Example 4

Embodiment 4 of the present invention provides a method for manufacturing a thin film bulk acoustic wave resonator, the manufacturing method comprising: S01: forming a first electrode, a second electrode and a piezoelectric layer, wherein the piezoelectric layer is located in the first electrode between the electrode and the second electrode; S02: forming a sacrificial layer on the first electrode, covering part of the first electrode; S03: forming a support layer, covering the sacrificial layer and the outer periphery of the sacrificial layer; S04: At least one of the first electrode and the second electrode has an arched bridge, and the method for forming an electrode with an arched bridge includes: forming an annular sacrificial protrusion; depositing a conductive material layer to cover the annular protrusion and the peripheral area of the annular protrusion to form an electrode with an arched bridge; S05: remove the annular sacrificial protrusion to form an annular space, and the area enclosed by the annular space is an effective resonance area of the resonator; S06: The sacrificial layer is removed to form a cavity.

It should be noted that, step S0N does not represent a sequence.

FIG. 4 to FIG. 8 are schematic structural diagrams corresponding to each step of the manufacturing method of the thin-film bulk acoustic resonator of the present embodiment. In the following, please refer to FIG. 4 to FIG. 8 to describe the manufacturing method of the thin film bulk acoustic resonator.

4 and 5, in this embodiment, the method for forming the first electrode, the second electrode and the piezoelectric layer includes: providing a carrier substrate 1000, forming the second electrode 103 on the carrier substrate 1000; A piezoelectric layer 102 is formed on the second electrode 103 ; a first electrode 101 is formed on the piezoelectric layer 102 , wherein the first electrode 101 is formed with an arch bridge structure 30 .

Specifically, referring to FIG. 4, a carrier substrate 1000 is provided, and the carrier substrate may be a semiconductor material such as silicon (Si), germanium (Ge), silicon germanium (SiGe), silicon carbon (SiC), silicon germanium carbon (SiGeC), Indium Arsenide (InAs), Gallium Arsenide (GaAs), Indium Phosphide (InP) or other III/V compound semiconductors. The second electrode 103 may be formed on the carrier substrate by a physical vapor deposition process, and the material of the second electrode 103 may refer to Embodiment 1. The piezoelectric layer 102 can be deposited and formed using any suitable method known to those skilled in the art, such as chemical vapor deposition, physical vapor deposition, or atomic layer deposition.

Referring to FIG. 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 a ring-shaped sacrificial protrusion 31, the sacrificial protrusion 31 is a continuous structure, enclosing a closed ring, and the ring-shaped boundary defines the boundary of the effective resonance area of the resonator. A first electrode is formed to cover 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 void. For the beneficial effect of forming the first electrode 101 with the arched bridge structure, please refer to Embodiment 1, and for the setting of the height of the annular sacrificial protrusion 31, please refer to the description about the gap height in Embodiment 1, which will not be repeated here.

Referring to FIG. 6 , a sacrificial layer material is deposited on the first electrode 101. For the selection of the sacrificial layer material, refer to the description in the previous paragraph. Pattern the sacrificial layer material to form a sacrificial layer 201. The sacrificial layer 201 covers the arched bridge area and The surrounding area exposes the peripheral first electrode 101 .

7 , a support layer 100 b is formed to cover the sacrificial layer 201 and the first electrode 101 , and the material of the support layer refers to Embodiment 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. The substrate 100a may be a semiconductor material or a dielectric material. Refer to Embodiment 1 for the type of material. The substrate 100a may be bonded to the support layer 100b by means of bonding, and the substrate 100a and the support layer 100b may be bonded by the bonding layer. For specific description, refer to Embodiment 1, which is not described here. The purpose of forming the substrate 100a is to make the bottom of the subsequently formed cavity 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.

8, the carrier substrate is removed to expose the second electrode 103. The carrier substrate may be removed by a grinding process or a wet etching process, or a release layer may be formed on the carrier substrate before the second electrode 103 is formed. The carrier substrate is peeled off by means of 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, the method further includes patterning the first electrode and the second electrode, so that the projections of the first electrode and the second electrode in the peripheral region of the arched bridge on the plane where the piezoelectric layer is located are staggered from each other. For the beneficial effect of this arrangement, refer to the relevant description of Embodiment 1.

The sacrificial layer is removed to form the cavity 200 . The method of removing the sacrificial layer can be selected according to the material of the sacrificial layer. When the material of the sacrificial layer is polyimide or photoresist, it is removed by ashing method. The oxygen in the pores chemically reacts with the sacrificial layer material, and the generated gaseous substances are volatilized. When the sacrificial layer material is low-temperature silicon dioxide, the hydrofluoric acid solvent and the low-temperature silicon dioxide are used to react and remove. The release holes may be formed in the edge region of the cavity. When the material of the annular sacrificial protrusion is the same as that of the sacrificial layer, the annular sacrificial protrusion may be removed together with the removal of the sacrificial layer. The annular sacrificial bump and sacrificial layer can also be removed in steps.

Example 5

FIG. 9 to FIG. 13 are schematic structural diagrams corresponding to each step of the manufacturing method of the thin-film bulk acoustic resonator of the present embodiment. In the following, please refer to FIG. 9 to FIG. 13 to describe the manufacturing method of the thin film bulk acoustic resonator. In this embodiment, the order in which the first electrode, the piezoelectric layer and the second electrode are formed is different.

Referring to FIG. 9 , a carrier substrate 1000 is provided, and a first electrode 101 with an arched bridge is formed on the carrier substrate. Refer to Embodiment 4 for the material and formation method of the related film layers.

Referring to 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 .

11 , a support layer 100b is formed on the sacrificial layer 201 and the first electrode 101, and the substrate 100a is bonded on the support layer 100b. Refer to Embodiment 4 for related process steps.

Referring to FIG. 12 , the carrier substrate is removed to expose the first electrode 101 and the annular sacrificial protrusion 31 , and the piezoelectric layer 102 is formed on the first electrode 101 and the annular sacrificial protrusion 31 , and the material and formation method of the piezoelectric layer are implemented with reference to Example 4.

13 , the second electrode 103 is formed, and the material and the forming method of the second electrode 103 refer to Embodiment 4.

Example 6

14 to 19 are schematic structural diagrams corresponding to each step of the manufacturing method of the thin film bulk acoustic resonator of the present embodiment. In the following, please refer to FIG. 14 to FIG. 19 to describe the manufacturing method of the thin film bulk acoustic resonator. In this embodiment, the order in which the first electrode, the piezoelectric layer and the second electrode are formed is different. In addition, the piezoelectric layer is further formed with a groove penetrating the piezoelectric layer.

Referring to FIG. 14 , a carrier substrate 1000 is provided, and the piezoelectric layer 102 is formed on the carrier substrate. Refer to Embodiment 4 for the carrier substrate 1000 , the material of the piezoelectric layer 102 and the method for forming the piezoelectric layer. The trench 40 is formed in the piezoelectric layer 102, and the trench 40 may be formed by a dry etching process including, but not limited to, reactive ion etching (RIE), ion beam etching, plasma etching or laser cutting. In this embodiment, the trench 40 is a closed ring and penetrates through the piezoelectric layer 102 , and the inner sidewall of the trench 40 coincides with the boundary of the effective resonance region of the resonator. In other embodiments, the grooves 40 may also be discontinuous annular structures or non-annular structures, for example, only provided at a certain side boundary of the effective resonance region. In other embodiments, the trenches 40 may also be disposed outside the effective resonance region. A trench 40 is formed in the piezoelectric layer 102, so that the end face of the piezoelectric layer 102 and the gas in the trench form a reflection interface, so as to effectively suppress the leakage of transverse waves in the piezoelectric layer and improve 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 the shear wave leakage is the best.

Referring to FIG. 15, a sacrificial material layer is formed, covering the piezoelectric layer 102, and the sacrificial material layer is filled into the trench. For the material and formation method of the sacrificial material layer, refer to Embodiment 4, pattern the sacrificial material layer, and form a ring shape above the trench Sacrifice bump 31 . With regard to the structure of the annular sacrificial protrusion 31 , reference is made to Embodiment 4 in height.

Referring to FIG. 16 , a first electrode 101 is formed to cover 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 and formed on the first electrode 101. The selection of the sacrificial layer material refers to the above. The sacrificial layer material is patterned to form a sacrificial layer 201. The sacrificial layer 201 covers the arched bridge area and the surrounding area of the arched bridge, exposing the outer periphery. the first electrode 101.

Referring to FIG. 17 , a support layer 100b is formed to cover the sacrificial layer 201 and the first electrode 101 , and the material of the support layer refers to Embodiment 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. The substrate 100a may be a semiconductor material or a dielectric material. Refer to Embodiment 1 for the type of material. The substrate 100a may be bonded on the support layer 100b by means of bonding.

Referring to FIG. 18 , the carrier substrate is removed to expose the piezoelectric layer 102 and the sacrificial material layer in the grooves in the piezoelectric layer 102 , and the method for removing the carrier substrate refers to Embodiment 4. A sacrificial material layer is formed to cover the piezoelectric layer 102 , and the sacrificial material layer is patterned to form an annular sacrificial protrusion 31 .

Referring to FIG. 19 , the second electrode 103 is formed to cover the annular sacrificial protrusion 31 and the piezoelectric layer 102, and the second electrode formed also has an arch bridge structure. The sacrificial layer, the sacrificial material in the piezoelectric layer, and the two annular protrusions are removed. In this embodiment, the two annular protrusions and the sacrificial layer material in the piezoelectric layer groove are connected to each other and can be removed simultaneously. The arched bridge of the first electrode and the arched bridge of the second and second electrodes formed in this embodiment are disposed opposite to each other, and the gap between the two arched bridges is communicated with the groove of the piezoelectric layer. Refer to Embodiment 1 for the beneficial effects of forming trenches in the piezoelectric layer.

Example 7

The present embodiment provides a method for manufacturing a thin-film bulk acoustic wave resonator, including: S01: providing a substrate with an acoustic mirror structure, and sequentially forming a first electrode and a piezoelectric layer on the substrate; S02: applying the pressure A ring-shaped sacrificial protrusion is formed on the electrical layer, and the ring-shaped protrusion is located above the area surrounded by the acoustic mirror structure; S03: a second electrode is formed, covering the piezoelectric layer and the ring-shaped sacrificial protrusion; S04: removal The annular sacrificial protrusion forms an annular space, and the area enclosed by the annular space is an effective resonance area of the resonator.

FIG. 20 is a schematic structural diagram of a thin-film bulk acoustic resonator manufactured according to the method for manufacturing a thin-film bulk acoustic resonator of the present embodiment. Referring to FIG. 20 , the manufacturing method includes: providing a substrate 300 with an acoustic mirror structure 310 , the material of the substrate 300 refers to the material of the first substrate in Embodiment 4, the acoustic mirror structure 310 is formed in the substrate 300 , and the acoustic mirror The structure 310 is such as a Bragg reflector structure. The first electrode 101 is formed on the upper surface of the substrate 300 , and the piezoelectric layer 102 is formed on the first electrode 101 . Refer to Embodiment 4 for materials and forming methods of the first electrode 101 and the piezoelectric layer 102 . A sacrificial material layer is formed on the piezoelectric layer 102, the sacrificial material layer is patterned, and an annular sacrificial protrusion is formed. 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 space, and the method for removing the annular sacrificial protrusion is referred to in Embodiment 4, which will not be repeated here.

It should be noted that each embodiment in this specification is 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 examples, the parts of the second and third embodiments that are the same as the first embodiment may refer to the first embodiment. For the method examples, the fifth, sixth and seventh embodiments are the same as the fourth embodiment. The part can refer to Example 4. The embodiments of the method and structure may refer to each other.

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 and modifications made by those of ordinary skill in the field of the present invention based on the above disclosure all belong to the protection scope of the claims.

Claims

A thin film bulk acoustic wave resonator is characterized in that it comprises: a piezoelectric laminated structure, the piezoelectric laminated structure includes 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 arched bridge protruding away from the surface of the piezoelectric layer, the inner surface of the arched bridge encloses an annular space, the annular space The enclosed area is the effective resonance area of the resonator.
The thin-film bulk acoustic wave resonator according to claim 1, wherein the arched bridge and the electrode material on which it is located are the same, and have an integral structure.
The thin film bulk acoustic wave resonator according to claim 1, wherein one of the first electrode and the second electrode is provided with the arch bridge; or, the first electrode and the second electrode are provided with the arch bridge; Both electrodes are provided with the arch bridge.
The thin-film bulk acoustic wave resonator according to claim 1, wherein 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 terminal.
The thin film bulk acoustic wave resonator according to claim 1, wherein the first electrode and the second electrode are not opposite to each other in a partial region outside the effective resonance region.
The thin film bulk acoustic wave resonator according to claim 1, wherein the piezoelectric laminated 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 is extending onto the first substrate outside the cavity.
The thin film bulk acoustic wave resonator according to claim 6, wherein the piezoelectric layer covers the cavity and extends outside the cavity.
The thin film bulk acoustic wave resonator according to claim 1, wherein a groove is formed in the piezoelectric layer, and the groove is opposite to the arch bridge.
The thin film bulk acoustic wave resonator according to claim 8, wherein the groove penetrates the piezoelectric layer.
The thin film bulk acoustic wave resonator according to claim 8, wherein the groove is a continuous structure or the groove is a discontinuous structure.
The thin-film bulk acoustic wave resonator according to claim 1, wherein the shape of the effective resonance region is an irregular polygon.
The thin film bulk acoustic wave resonator according to claim 1, wherein the piezoelectric laminated structure is located on the second substrate having an acoustic mirror.
The thin film bulk acoustic wave resonator according to claim 6, wherein the first substrate comprises a base and a support layer, and the support layer and the piezoelectric laminated structure are sequentially stacked on the base, so that the The cavity is disposed in the support layer; or the first substrate is a semiconductor substrate, and the cavity is located on the upper surface of the semiconductor substrate.
The thin film bulk acoustic wave resonator according to claim 13, wherein the cavity penetrates through the support layer; or, the cavity extends to a part of the thickness of the support layer.
The thin film bulk acoustic wave resonator of claim 14, wherein the material of the substrate comprises a semiconductor material, and the material of the support layer comprises a dielectric material.
The thin film bulk acoustic wave resonator according to claim 1, wherein the material of the first electrode or the second electrode comprises: molybdenum, aluminum, copper, tungsten, tantalum, platinum, ruthenium, rhodium, iridium, A combination of one or more of chromium, titanium, gold, osmium, rhenium, or palladium.
The thin film bulk acoustic wave resonator according to claim 1, wherein the piezoelectric layer is made of: aluminum nitride, zinc oxide, lead zirconate titanate, lithium niobate, quartz, potassium niobate or tantalic acid lithium.
A filter comprising at least one thin-film bulk acoustic resonator as claimed in any one of claims 1 to 17.
A method for manufacturing a thin film bulk acoustic resonator, comprising: 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, covering part of the first electrode; forming a support layer, covering the sacrificial layer and the outer periphery of the sacrificial layer; the first electrode, the second electrode at least wherein One of the electrodes has an arched bridge, and a method for forming an electrode with an arched bridge includes: forming an annular sacrificial protrusion; The electrode of the arch bridge; the annular sacrificial protrusion is removed to form an annular space, and the area enclosed by the annular space is an effective resonance area of the resonator; the sacrificial layer is removed to form a cavity.
The method for manufacturing a thin film bulk acoustic resonator according to claim 19, wherein the method for forming the first electrode, the second electrode and the piezoelectric layer comprises: providing a carrier substrate; on the carrier substrate forming a first electrode; 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 provide a carrier substrate; form a second electrode on the carrier substrate; form a piezoelectric layer on the second electrode; form a first electrode on the piezoelectric layer; after forming the support layer, remove the carrier substrate.
The method for manufacturing a thin film bulk acoustic resonator according to claim 19, wherein the formed piezoelectric layer covers the cavity and extends outside the cavity; or,

After the piezoelectric layer is formed, the piezoelectric layer is etched to form trenches extending through the piezoelectric layer, the trenches being opposite to the arched bridges.
The method for manufacturing a thin-film bulk acoustic resonator according to claim 21, wherein the groove is a closed ring shape, or the groove is provided intermittently, and the piezoelectric layer in the effective resonance region passes through the discontinuity. is connected to the piezoelectric layer outside the effective resonance region.
The method for manufacturing a thin film bulk acoustic resonator according to claim 22, wherein the groove communicates with the gap.
The method for manufacturing a thin film bulk acoustic resonator according to claim 19, wherein the first electrode and the second electrode extend from the effective resonance region to the periphery of the cavity.
The method for manufacturing a thin film bulk acoustic resonator according to claim 19, wherein forming the first electrode and the second electrode further comprises patterning the first electrode and the second electrode, so that the The projections of the first electrode and the second electrode are offset from each other at the periphery of the cavity.
The method for manufacturing a thin-film bulk acoustic wave resonator according to claim 19, wherein the material of the annular sacrificial protrusions comprises phosphosilicate glass, low temperature silicon dioxide, borophosphosilicate glass, germanium, carbon, polyimide Amine or photoresist.
A method for manufacturing a thin-film bulk acoustic wave resonator is characterized by comprising: providing a substrate with an acoustic mirror structure, forming a first electrode and a piezoelectric layer on the substrate in sequence; forming a ring on the piezoelectric layer a sacrificial protrusion, the annular protrusion is located above the area surrounded by the acoustic mirror structure; a second electrode is formed to cover the piezoelectric layer and the annular sacrificial protrusion; the annular sacrificial protrusion is removed to form an annular space , the area enclosed by the annular gap is the effective resonance area of the resonator.