WO2022057765A1

WO2022057765A1 - Method for manufacturing film bulk acoustic resonator, and filter

Info

Publication number: WO2022057765A1
Application number: PCT/CN2021/117992
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: CN114257193A

Abstract

The present invention relates to a method for manufacturing a film bulk acoustic resonator and a filter. The method comprises: forming a first substrate having a first sacrificial layer; sequentially forming a first electrode, a piezoelectric layer and a second electrode, the first electrode covering the first sacrificial layer; forming, on at least one of the first electrode and the second electrode, an annular trench extending through the corresponding electrode; forming, on the corresponding electrode on which the annular trench is formed, an electrode lead-out structure having an arch bridge structure, the arch bridge structure being opposite to the annular trench; and removing the first sacrificial layer to form a first cavity. According to the present invention, the boundary of an effective resonance region is defined by a region in which an annular gap of an electrode lead-out structure is located, and arrangement of an annular trench enables an end portion of a corresponding electrode at the boundary of the effective resonance region to be in contact with a gas in the gap, thereby achieving the effect of eliminating clutter at the boundary of the effective resonance region for the electrode, and accordingly increasing the Q value of a resonator.

Description

Manufacturing method and filter of thin-film bulk acoustic wave resonator

technical field

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

Background technique

Since analog RF communication technology was developed in the early 1990s, RF front-end modules have gradually become the core components of communication equipment. Among all RF front-end modules, filters have become the most rapidly growing and most promising components. With the rapid development of wireless communication technology, the 5G communication protocol is becoming more and more mature, and the market has put forward stricter standards for the performance of RF filters in all aspects. The performance of the filter is determined by the resonator units that make up the filter. Among existing filters, thin-film bulk acoustic resonators (FBARs) are characterized by their small size, low insertion loss, large out-of-band suppression, high quality factor, high operating frequency, large power capacity, and good anti-static shock capability. Become one of the most suitable filters for 5G applications.

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 quality factor (Q) of the cavity-type thin-film bulk acoustic wave resonators produced at present cannot be further improved, so it cannot meet the needs of high-performance radio frequency systems.

technical solutions

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

In order to achieve the above object, the present invention provides a method for manufacturing a thin film bulk acoustic resonator, which is characterized by comprising: forming a first substrate having a first sacrificial layer; forming a first electrode, forming a piezoelectric layer and forming a second electrode, the first electrode covering the first sacrificial layer; forming an annular groove penetrating the corresponding electrode on at least one of the first electrode and the second electrode; forming a corresponding electrode with the annular groove An electrode lead-out structure with an arched bridge structure is formed thereon, and the arched bridge structure is opposite to the annular groove; the first sacrificial layer is removed to form a first cavity.

The present invention also provides a filter, comprising at least one thin-film bulk acoustic resonator formed by the above-mentioned manufacturing method of the thin-film bulk acoustic resonator.

beneficial effect

The beneficial effect of the method for manufacturing a thin film bulk acoustic wave resonator of the present invention is that: forming annular grooves on the first electrode and/or the second electrode by etching, so as to disconnect the corresponding electrodes, and then forming arches on the corresponding electrodes The electrode lead-out structure of the bridge-shaped structure is used to electrically connect the disconnected electrode parts; the boundary of the corresponding electrode is exposed to the annular gap formed by the arch-shaped bridge through the annular groove formed on the corresponding electrode, so as to eliminate the effective resonance area. The effect of the electrode boundary clutter is increased, thereby improving the Q value of the resonator; the formation of the first cavity by etching the support layer can simplify the formation process and reduce the manufacturing cost.

Further, when the electrode lead-out structure is formed on the first electrode, the process steps can be simplified by directly forming the electrode lead-out structure on the first substrate and then forming the first electrode on the electrode lead-out structure; A cavity is filled with the first sacrificial layer, so that the subsequently formed first electrode can be kept flat, so that the piezoelectric layer can be formed on the flat first electrode, so that the upper surface and the lower surface of the piezoelectric layer are both flat, It is ensured that the piezoelectric layer has a good lattice orientation, and the piezoelectric properties of the piezoelectric layer are improved, thereby improving the performance of the resonator.

Further, when the electrode lead-out structure is formed on the second electrode, an electrode lead-out structure with an arched bridge structure is formed by forming an annular sacrificial protrusion, and an annular gap is formed after the annular sacrificial protrusion is removed, which is convenient for simplifying the electrode. The forming process of the lead-out structure can separate the electrodes located inside and outside the annular groove, and electrically connect the disconnected electrodes through the electrode lead-out structure, thereby reducing the resistance of the electrodes.

Further, the impedance of the electrode lead-out structure is lower than the impedance of the corresponding electrode, so as to reduce the electrode impedance, make the electrode lead-out structure have better conductivity, and improve the conductivity.

Further, the projections of the first electrode and the second electrode in the peripheral area of the arched bridge on the plane where the piezoelectric layer is located are at least partially staggered from each other, which can avoid the problem of high-frequency coupling caused by potential floating, prevent the formation of parasitic capacitance, and is conducive to improving Resonator quality factor. Similarly, when both the first electrode and the second electrode are provided with an electrode lead-out structure, the projections of the two on the plane where the piezoelectric layer is located are at least partially staggered from each other, and the problem of high frequency coupling can also be avoided.

Further, the first electrode and the second electrode extend from the effective resonance region to the first substrate on the periphery of the first cavity, which can improve the structural strength of the resonator. In addition, the electrode lead-out structure formed on the corresponding electrode also reduces the effective The resonance region extends to the first substrate on the periphery of the first cavity, so as to improve the structural strength of the resonator.

Further, the piezoelectric layer is a complete film layer, which can ensure the structural strength of the resonator and improve the yield of the resonator.

Further, the piezoelectric layer is provided with a first groove, 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.

The beneficial effect of the filter of the present invention is that the filter is formed by connecting the above-mentioned thin-film bulk acoustic wave resonators, so as to ensure that the filter has good structural stability, and the electrode impedance of the resonator is low, which can improve the performance of the filter. Conductivity, improve the accuracy of filtering.

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.

1 is a flowchart of a method for manufacturing a thin-film bulk acoustic resonator according to Embodiment 1 of the present invention; FIGS. 2 to 6 show structural schematic diagrams corresponding to different steps of the method for manufacturing a thin-film bulk acoustic resonator according to Embodiment 1 of the present invention; Fig. 7 shows a schematic structural diagram corresponding to different steps of another method for manufacturing a thin-film bulk acoustic resonator formed in Example 2 of the present invention; Fig. 8 shows a thin film manufactured by the method for manufacturing a thin-film bulk acoustic resonator in Example 3 of the present invention Schematic diagram of the structure of the bulk acoustic wave resonator; FIG. 9 is a schematic diagram of the structure of the thin film bulk acoustic wave resonator manufactured by the manufacturing method of the thin film bulk acoustic wave resonator according to Embodiment 4 of the present invention.

1. The first substrate; 11, the base; 12, the support layer; 121, the first cavity; 121', the first sacrificial layer; 13, the first groove; 1414, the second groove; 21, first electrode; 22, piezoelectric layer; 23, second electrode; 24, annular groove; 25, first groove; 3, first electrode lead-out structure; 31, first arch bridge; 32, first an annular space; 32', the first annular sacrificial protrusion; 4, the second electrode lead-out structure; 41, the second arch bridge; 42, the second annular space; 42', the second annular sacrificial protrusion; 5, the bearing Substrate; 6. Second substrate; 61. Second sacrificial layer; 7. Temporary 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

1 is a flow chart of a method for manufacturing a thin film bulk acoustic resonator according to Embodiment 1 of the present invention. Referring to FIG. 1 , Embodiment 1 provides a method for manufacturing a thin film bulk acoustic resonator. The method for manufacturing a thin film bulk acoustic resonator includes: : S01: forming a first substrate with a first sacrificial layer; S02: sequentially forming a first electrode, forming a piezoelectric layer and forming a second electrode on the first substrate, the first electrode covering the first sacrificial layer; S03: An annular groove penetrating the corresponding electrode is formed on at least one of the first electrode and the second electrode; an electrode lead-out structure having an arched bridge structure is formed on the corresponding electrode formed with the annular groove, and the arched bridge structure is connected to the annular groove. The grooves are opposite; S04: remove the first sacrificial layer to form a first cavity.

Step S0N does not represent a sequential order.

In this embodiment, the first electrode 21 and the second electrode 24 both form an electrode lead-out structure, and the electrode lead-out structure formed on the first electrode 21 is hereinafter referred to as the first electrode lead-out structure 3 to be formed on the second electrode 23 The electrode extraction structure is the second electrode extraction structure. 2 to 7 are schematic structural diagrams corresponding to corresponding steps of a method for manufacturing a thin film bulk acoustic resonator according to the present embodiment, and the manufacturing method of the thin film bulk acoustic wave resonator provided by the present embodiment is described in detail with reference to FIGS. 2 to 7 .

Referring to FIG. 2, a first substrate 1 having a first sacrificial layer 121' is formed. In this embodiment, the first substrate 1 includes a support layer 12 and a base 11 , and the method for forming the first substrate 1 with the first sacrificial layer 121 ′ includes: providing the base 11 ; forming the support layer 12 on the base 11 ; The support layer 12 is patterned to form a first cavity; the first cavity is filled to form a first sacrificial layer 121 ′. The first surface of the first sacrificial layer 121 ′ is flush with the first surface of the support layer 12 . It should be noted that the first surface of the support layer 12 is the surface of the support layer 12 adjacent to the first electrode 21, and the first surface of the first sacrificial layer 121' is also the surface adjacent to the first electrode 21. The first sacrificial layer 121 ′ can be formed by deposition. In order to ensure that the first surface of the first sacrificial layer 121 ′ is flush with the first surface of the supporting layer 12 , the first sacrificial layer 121 ′ formed by deposition also needs to be flattened. The planarization process can use a chemical mechanical polishing process to ensure that the first electrode, the piezoelectric layer and the second electrode formed subsequently are formed on the flat layer, so that the first electrode, the piezoelectric layer and the second electrode are kept flat . The material of the first sacrificial layer 121' includes phosphosilicate glass, low temperature silicon dioxide, borophosphosilicate glass, germanium, amorphous carbon, polyimide or photoresist.

The support layer 12 can be bonded to the substrate 11 by means of a bonding layer. The material of the bonding layer includes silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride or ethyl silicate. In addition, the bonding layer can also use adhesives such as light-curing materials or heat-curing materials, such as adhesive film (Die Attach Film, DAF) or dry film (Dry Film), etc. In addition, the support layer 12 can also be formed on the substrate 11 by means of deposition, and the deposition process includes chemical vapor deposition and physical vapor deposition. The material of the substrate 11 may be at least one of the following materials: 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 material of the support layer 12 includes a dielectric material such as silicon dioxide, silicon nitride, aluminum oxide, aluminum nitride, silicon oxynitride, or silicon carbonitride.

The first cavity may be formed on the support layer 12 by etching, and the first cavity penetrates a part of the support layer 12 , that is, the first cavity extends to a part of the thickness of the support layer 12 . In other embodiments, the first cavity completely penetrates the support layer 12 . In this embodiment, the cross-sectional shape of the first cavity may be a rectangle, but in other embodiments of the present invention, the cross-sectional shape of the first cavity may also be a circle, an ellipse, or a polygon other than a rectangle, For example, pentagons, hexagons, etc. The shape of the first sacrificial layer 121' is the same as that of the first cavity.

In another embodiment, the first substrate 1 includes a semiconductor substrate, and the method for forming the first substrate 1 with the first sacrificial layer 121' includes: providing the first substrate 1; etching the first substrate 1, forming a first cavity, the first cavity extending to a part of the thickness of the first substrate 1; filling the first cavity to form a first sacrificial layer 121', the first surface of the first sacrificial layer 121' and the first substrate 1 is flush with the first surface.

Referring to FIGS. 3-4 , before forming the first electrodes, a first electrode lead-out structure 3 having a first arch bridge 31 structure is formed on the first sacrificial layer 121 ′, and the first electrode lead-out structure 3 extends to the first sacrificial layer 121 ′. on the first substrate 1 at the periphery of the layer 121'. Specifically: referring to FIG. 3 , a first groove 13 is formed on the first sacrificial layer 121 ′, and the first groove 13 is located around the effective resonance area; The depth of the groove 14 is greater than that of the first groove 13, and the second groove 14 is located at the edge of the effective resonance area. It should be noted that the second groove 14 encloses a closed annular shape, so that the subsequently formed first arch bridge 31 structure and the first annular sacrificial protrusion 32' in it enclose a closed annular shape, so that the removal of the first annular shape The first annular space 32 formed after the sacrificial protrusion 32' forms a closed ring, the area enclosed by the first annular sacrificial space is an effective resonance area, and the surrounding area of the effective resonance area is the part of the first annular space outside the effective resonance area. In the sacrificial layer 121', the edge of the effective resonance region is defined by the boundary of the second annular sacrificial protrusion.

In order to facilitate the subsequent electrical connection of the first electrode lead-out structure 3 formed in the first groove 13 with the outside, the first electrode lead-out structure 3 needs to have a second portion extending outside the effective resonance area to serve as an electrode connection terminal. Therefore, The first groove 13 may extend from the periphery of the effective resonance area to the first substrate 1 on the periphery of the first sacrificial layer 121 ′, so that the subsequently formed first electrode lead-out structure 3 extends from the periphery of the effective resonance area to the first substrate 1 . On the first substrate 1 at the periphery of the sacrificial layer 121'; alternatively, the first groove 13 may extend from a part of the effective resonance region to the first substrate 1 at the periphery of the first sacrificial layer 121'. It should be noted that, the first groove 13 may be formed on the first sacrificial layer 121' and the first substrate 1 through an etching process. For the material of the first annular sacrificial protrusion 32', reference may be made to the material of the first sacrificial layer 121' described above.

Because when the first groove 13 extends from a part of the effective resonance area to the first substrate 1 on the periphery of the first sacrificial layer 121 ′, part of the subsequently formed first electrode lead-out structure 3 extends from the periphery of the annular sacrificial protrusion to the first substrate 1 on the periphery of the first sacrificial layer 121 ′, therefore, in order to keep the surface of the first electrode lead-out structure 3 and the first substrate 1 flush, a dielectric layer is also formed on the first substrate 1 , The dielectric layer is in continuous contact with the first electrode lead-out structure 3 or has a gap, and the dielectric layer is flush with the surface of the first electrode lead-out structure facing the first electrode, so that the electrodes can be formed on a flat surface.

Referring to FIG. 4 , a first electrode lead-out structure 3 is formed in the first groove 13 , and the first electrode lead-out structure 3 fills the first groove 13 outside the second groove 14 ; A first annular sacrificial protrusion 32' is formed on an electrode lead-out structure 3; the first annular sacrificial protrusion 32' is removed to form a first annular space. It should be noted that the first electrode lead-out structure 3 can be formed in the first groove 13 and the second groove 14 by means of deposition, and the part formed in the second groove 14 forms the first arch bridge 31 structure . The deposition method includes physical vapor deposition or chemical vapor deposition. In order to form the electrodes formed subsequently on a flat surface, the first annular sacrificial protrusion 32', the first sacrificial layer 121' and the first substrate 1 may be flattened so that the surfaces of the three are kept flush. In this embodiment, the first annular sacrificial protrusion 32' may be removed together with the first sacrificial layer 121' later, and the specific steps are described below. In other embodiments, the first annular sacrificial protrusion 32 ′ can also be removed before forming the first electrode 21 , but in order to keep the subsequently formed first electrode 21 flat, it needs to be filled with a sacrificial material to make the first electrode 21 flat. The upper surface is flush with the upper surface of the first electrode 21 .

The first electrode lead-out structure 3 further includes an overlap portion connecting the first arch bridge structure 31 and extending to the periphery of the first sacrificial layer 121 ′, and the overlap portion surrounds part or all of the periphery of the first electrode 21 . Specifically, the overlapping portion may partially extend to the outer edge of the first substrate 1 at the periphery of the first sacrificial layer 121 ′, or may entirely extend to the outer edge of the first substrate 1 at the periphery of the first sacrificial layer 121 ′, so as to For electrical connection with the outside, when the overlapping portion extends to the outer edge of the first substrate 1 at the periphery of the first sacrificial layer 121 ′, the structural strength of the resonator is better. In addition, the first electrode lead-out structure 3 may be distributed on the first electrode 21 without etching, that is, the overlapping portion may be a planar structure and laid on the first electrode 21; or, the first electrode lead-out structure 3 may be Etching is performed to form a plurality of strip-shaped overlapping parts, and the multiple strip-shaped overlapping parts can be symmetrically distributed on the first electrode 21 to improve the structural strength of the resonator. Since the first electrode lead-out structure 3 only needs to connect the first electrode 21 disconnected by the annular groove 24 and extend to the first substrate 1 on the periphery of the first sacrificial layer 121 ′, the specific The structure is not further limited. In this embodiment, the impedance of the first electrode lead-out structure 3 is lower than that of the first electrode, so that the first electrode with the annular groove formed subsequently is connected through the first electrode lead-out structure 3 and will be disconnected by the annular groove connected to the first electrode, thereby reducing the impedance of the first electrode. The material of the first electrode extraction structure 3 is a metal material, and the metal material includes one or more of gold, silver, tungsten, platinum, aluminum, copper, titanium, tin, and nickel.

Continuing to refer to FIG. 4 , a first electrode 21, a piezoelectric layer 22 and a second electrode 23 are sequentially formed on the first substrate 1, and the first electrode 21 covers the first sacrificial layer 121'. The first electrode 21 and the second electrode 23 can be formed by a physical vapor deposition process and an etching process, and the periphery of the first electrode 21 and the second electrode 23 extends to the first substrate 1 on the periphery of the first sacrificial layer 121 ′, In order to improve the structural strength of the resonator. In other embodiments, when the first electrode 21 and the second electrode 23 are formed, the corresponding electrodes are etched, so that the peripheries of part of the first electrode 21 and part of the second electrode 23 extend to the second part of the periphery of the first sacrificial layer 121 ′ on a substrate 1.

The piezoelectric layer 22 may be deposited using any suitable method known to those skilled in the art, such as chemical vapor deposition, physical vapor deposition, or atomic layer deposition. By forming the piezoelectric layer 22 on the flat first electrode 21, the upper surface and the lower surface of the piezoelectric layer 22 are both flat, so as to ensure that the piezoelectric layer 22 has a better lattice orientation, and improve the piezoelectric layer 22. piezoelectric properties, thereby improving the overall performance of the resonator. It should be noted that the effective resonance area is the area surrounded by the first annular gap 32 formed subsequently.

The material of the first electrode 21 and the second electrode 23 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 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 22 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 22 is made of aluminum nitride (AlN), the piezoelectric layer 22 may further include rare earth metals such as at least one of scandium (Sc), erbium (Er), yttrium (Y) and lanthanum (La). . In addition, when the material of the piezoelectric layer 22 is aluminum nitride (AlN), the piezoelectric layer 22 may further include transition metals such as zirconium (Zr), titanium (Ti), manganese (Mn), and hafnium (Hf). at least one.

4, in this embodiment, after the second electrode 23 is formed, the second electrode 23 is etched to form a trench penetrating the second electrode 23, the piezoelectric layer 22 and the first electrode 21, wherein the trench The part penetrating the second electrode 23 and the first electrode 21 is the annular groove 24 , the part of the groove penetrating the piezoelectric layer 22 is the first groove 25 , and the groove penetrating the first electrode 21 and the second electrode 23 to The first electrode 21 and the second electrode 23 are cut off at the trench, and then the cut off first electrode 21 is electrically connected through the first electrode lead-out structure 3 formed on the first electrode 21, and the second electrode 23 is subsequently formed on the second electrode 23. The second electrode extraction structure 4 on the top is electrically connected to the second electrode 23 that is cut off, thereby reducing the impedance of the first electrode 21 and the second electrode 23 .

The annular groove 24 is opposite to the first annular sacrificial protrusion 32 ′, so that after the first annular sacrificial protrusion 32 ′ is subsequently removed to form the first annular space 32 , the annular groove 24 is opposite to the first annular space 32 , so that the The edge of the first electrode 21 is exposed in the first annular gap 32, thereby achieving the effect of eliminating electrode boundary clutter in the effective resonance region, so as to improve the Q value of the resonator. It should be noted that when the annular groove 24 is opposite to the first annular gap 32, the projection of the annular groove 24 on the surface of the piezoelectric layer 22 partially overlaps with the projection of the first annular gap 32 on the surface of the piezoelectric layer 22; or, The projection of the annular groove 24 on the surface of the piezoelectric layer 22 is completely within the projection range of the first annular gap 32 on the surface of the piezoelectric layer 22 . When the projection of the annular groove 24 on the surface of the piezoelectric layer 22 is completely within the projection range of the first annular gap 32 on the surface of the piezoelectric layer 22, the sound wave suppression effect is better.

In addition, the projections of the annular groove 24 and the first groove 25 on the surface of the piezoelectric layer 22 overlap each other, so that the edge of the piezoelectric layer 22 is exposed in the first annular gap 32 , thereby effectively suppressing the acoustic wave loss of the piezoelectric layer 22 . The first groove 25 is a closed annular shape, and the piezoelectric layer 22 around the first annular gap 32 and the piezoelectric layer 22 around the first annular gap 32 are isolated from each other; The piezoelectric layer 22 surrounding an annular gap 32 is isolated from the piezoelectric layer 22 surrounding the first annular gap 32 by discontinuities. When the first groove 25 is a closed annular shape, the effect of suppressing sound wave leakage is better.

5, after the second electrode 23 is formed, a second electrode lead-out structure 4 having a second arch bridge structure 41 is formed on the second electrode 23, and the second electrode lead-out structure 4 extends from the periphery of the effective resonance area to the first A sacrificial layer 121' is on the first substrate 1 at the periphery. Specifically, the second electrode is etched to form an annular groove 24, and the annular groove 24 is located within the range of the first sacrificial layer 121'; the annular groove 24 is filled to form a second annular sacrificial protrusion 42', and the second annular sacrificial protrusion 42 'The second electrode 23 covering the peripheral area of the annular groove 24; the second electrode lead-out structure 4 is formed on the second electrode 23, covering the second annular sacrificial protrusion 42', and extending to the first sacrificial layer 121' On a substrate 1, the second electrode lead-out structure 4 covers at least part of the second electrode 23 in the effective resonance area; the second annular sacrificial protrusion 42' is removed to form an annular space and an annular groove. It should be noted that the second electrode lead-out structure 4 located on the second annular sacrificial protrusion 42' forms a second arch bridge 41 structure.

In this embodiment, the method for forming the second electrode lead-out structure 4 on the second electrode 23 includes: depositing a conductive material on the second electrode 23 , and the conductive material covers the second electrode 23 and the first electrode formed on the second electrode 23 . Two annular sacrificial protrusions 4; Etch the conductive material, remove part of the conductive material located in the area surrounded by the second annular sacrificial protrusion 42', form a second electrode lead-out structure 4, and the second electrode lead-out structure 4 extends to the first on the first substrate 1 at the periphery of the sacrificial layer 121'. In other embodiments, the method for forming the second electrode lead-out structure 4 on the second electrode 23 includes: depositing a conductive material on the second electrode 23 to form the second electrode lead-out structure 4 , and the second electrode lead-out structure 4 covers the second electrode lead-out structure 4 . The electrode 23 and the second annular sacrificial protrusion 42' formed on the second electrode 23 extend to the first substrate on the periphery of the first sacrificial layer 121'. In the actual manufacturing process, the second electrode lead-out structure 4 only needs to be used to connect the second electrode 23 disconnected by the annular groove, and a corresponding formation method can be selected according to the actual structure, which is not further limited in this application. The structure of the second electrode lead-out structure 4 and its positional relationship with the second electrode 23 can be referred to the structure of the first electrode lead-out structure 3 and its positional relationship with the first electrode 21 , which will not be repeated here.

It should be noted that the formed second electrode lead-out structure 4 has a second portion extending outside the effective resonance area to serve as an electrode connection terminal, and the second electrode lead-out structure may partially extend from the periphery of the effective resonance area to the first sacrificial layer 121 ′ on the first substrate 1 at the periphery; or all extend from the periphery of the effective resonance region to the first substrate 1 at the periphery of the first sacrificial layer 121 ′.

Since the second annular space inside the second arch bridge structure 41 and the first annular space inside the first arch bridge structure 31 both form an effective resonance area, in order to avoid the effective resonance area enclosed by the corresponding annular space being staggered from each other, The first arched bridge structure 31 of the first electrode lead-out structure 3 and the second arched bridge structure 41 of the second electrode lead-out structure 4 are disposed opposite to each other, that is, the second arched bridge structure 41 and the first arched bridge are disposed The projections of the structures 31 on the surface of the piezoelectric layer 22 completely overlap. In addition, since the first electrode lead-out structure 3 and the second electrode lead-out structure 4 extend to the overlap portion on the first substrate 1 on the periphery of the first sacrificial layer 121 ′ only to connect external circuits and improve the strength of the resonator, Therefore, the projections of the overlapping portion of the first electrode extraction structure 3 and the overlapping portion of the second electrode extraction structure 4 on the surface of the piezoelectric layer 22 may overlap, partially overlap or not overlap at all.

The first electrode lead-out structure 3 and the second electrode lead-out structure 4 are at least partially staggered at the periphery of their corresponding arch bridge structures to avoid high-frequency coupling problems caused by potential floating, prevent the formation of parasitic capacitance, and further improve the quality of the resonator factor. When the electrode lead-out structure disposed on the first electrode 21 and the electrode lead-out structure disposed on the second electrode 23 are completely staggered at the periphery of the annular gap, the problem of high frequency coupling can be better avoided.

In other embodiments, after the first electrode 21 is formed and before the piezoelectric layer 22 is formed, the first electrode 21 may be etched to form an annular trench. The sacrificial material is filled in the annular groove, and the upper surface of the annular groove is kept flat with the first electrode 21 . Then, the piezoelectric layer 22 is formed thereon, and the second electrode 23 is formed; the second electrode 23 is etched to form a groove penetrating the second electrode 23 and the piezoelectric layer 22, wherein the part passing through the second electrode 23 is an annular groove , the part passing through the piezoelectric layer 22 is the first trench. For the remaining steps, refer to the above-mentioned Embodiment 1, which will not be repeated here.

In other embodiments, after the first electrode 21 is formed and before the piezoelectric layer 22 is formed, the first electrode 21 may be etched to form an annular trench. The sacrificial material is filled in the annular groove, and the upper surface of the annular groove is kept flat with the first electrode 21 . Then, the piezoelectric layer 22 is formed thereon; the piezoelectric layer 22 is etched to form a first groove penetrating the piezoelectric layer 22, and the first groove is opposite to the annular groove formed on the first electrode 21; The groove is filled with sacrificial material, and its upper surface is flush with the upper surface of the piezoelectric layer 22 . Then, a second electrode 23 is formed thereon; the second electrode 23 is etched to form an annular groove penetrating the second electrode 23; the annular groove of the second electrode 23 is filled with sacrificial material and covers the first part of the peripheral region of the annular groove; Two electrodes 23 form a second annular sacrificial protrusion; and a second electrode lead-out structure 4 is formed on the second electrode 23 to cover the second annular sacrificial protrusion 42'. For the remaining steps, refer to the above-mentioned Embodiment 1, which will not be repeated here.

Referring to FIG. 6 , the first sacrificial layer is removed to form a first cavity 121 . Specifically, a release hole is formed on the second electrode 23 through the second electrode 23 , the piezoelectric layer 22 and the first electrode 21 , so that the release hole extends to the first sacrificial layer, and the first sacrificial layer is removed through the release hole. In the process of removing the first sacrificial layer, according to the material of the first sacrificial layer, a corresponding removal method is adopted. For example, when the material of the first sacrificial layer is polyimide or photoresist, ashing method is used to remove it. The specific ashing method is that at a temperature of 250 degrees Celsius, oxygen chemically reacts with the sacrificial layer material through the air, and the generated gaseous substances are volatilized. When the first sacrificial layer material is low-temperature silicon dioxide, use hydrofluoric acid solvent and The silicon dioxide is removed by reaction to form a first cavity 121, and the shape of the first cavity 121 is the same as that of the first sacrificial layer. It should be noted that the above-mentioned first annular sacrificial protrusions 32' and second annular sacrificial protrusions 42' can be removed simultaneously with the first sacrificial layer, or can be removed before or after removing the first sacrificial layer. The removal method of the sacrificial layer will not be repeated here.

Example 2

Embodiment 2 provides a method for manufacturing a thin-film bulk acoustic resonator. FIG. 7 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 in this embodiment. The difference is that the piezoelectric layer 22 in the first embodiment is formed with the first groove 25, and the piezoelectric layer 22 in this embodiment is a complete film layer, and the etching of the piezoelectric layer 22 in the above-mentioned embodiment 1 is omitted. For this step, the remaining steps refer to Example 1 above. Specifically, the piezoelectric layer 22 is a complete film layer without etching, covering the first cavity 121 and extending to the first substrate 11 outside the first cavity 121 to ensure the structural strength of the resonator and improve the Resonator yield.

Example 3

Embodiment 3 provides a method for manufacturing a thin-film bulk acoustic resonator. The difference between this embodiment and Embodiment 1 is that an electrode lead-out structure is formed on both the first electrode 21 and the second electrode 23 in Embodiment 1. In 3, the electrode extraction structure is formed only on the first electrode 21 or the second electrode 23 . When the electrode lead-out structure is formed on the first electrode 21, the step of forming the second electrode lead-out structure 4 on the second electrode 23 in Embodiment 1 can be omitted; when the electrode lead-out structure is formed on the second electrode 23, the The step of forming the first electrode lead-out structure 3 on the first electrode 21 in Embodiment 1 is omitted. The structure of the thin film bulk acoustic resonator is described below by taking the formation of the first electrode lead-out structure 3 on the first electrode 21 as an example, and the formation of the second electrode lead-out structure 4 on the second electrode 23 can be referred to in the first A first electrode lead-out structure 3 is formed on the electrode 21 , which will not be repeated here. Referring to FIG. 8 , FIG. 8 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.

In this embodiment, the first electrode lead-out structure 3 is formed, and after the first electrode 21 and the piezoelectric layer 22 are formed, the piezoelectric layer 22 is etched to form a trench penetrating the piezoelectric layer 22 and the first electrode 21 . , the part passing through the piezoelectric layer 22 is the first groove 25, and the part passing through the first electrode 21 is the annular groove 24; the sacrificial material is filled in the groove, and its upper surface is aligned with the upper surface of the piezoelectric layer 22 flat; the second electrode 23 is formed on the piezoelectric layer 22 . For the remaining steps, refer to Embodiment 1, which will not be repeated here. In other embodiments, after the first electrode 21 is formed, the first electrode 21 is etched to form an annular trench 24 penetrating the first electrode 21; The top surface of an electrode 21 is flush; then a piezoelectric layer 22 is formed on the first electrode 21; the piezoelectric layer 22 is etched to form a first trench 25 penetrating the piezoelectric layer 22; material so that the upper surface is flush with the upper surface of the piezoelectric layer 22 ; and the second electrode 23 is formed on the piezoelectric layer 2222 .

In addition, when the electrode extraction structure is formed on the second electrode 23, the annular groove 24 penetrating the second electrode 23 and the first groove 25 penetrating the piezoelectric layer 22 can be formed simultaneously after the formation of the second electrode 23, refer to the above content. For the remaining steps, refer to Embodiment 1, which will not be repeated here. In other embodiments, the first groove 25 penetrating the piezoelectric layer 22 and the annular groove 24 penetrating the second electrode 23 may be formed after the piezoelectric layer 22 and the second electrode 23 are formed correspondingly, as described above for details. For the remaining steps, refer to Embodiment 1, which will not be repeated here.

It should be noted that the electrode lead-out structure and the corresponding electrode without the electrode lead-out structure are at least partially staggered at the periphery of the arched bridge structure to avoid the high-frequency coupling problem caused by the floating potential, prevent the formation of parasitic capacitance, and further improve Resonator quality factor. When the electrode lead-out structure and the corresponding electrode without the electrode lead-out structure are completely staggered at the periphery of the arched bridge structure, the problem of high frequency coupling can be better avoided. The corresponding electrode can be understood as, when the electrode lead-out structure is formed on the first electrode 21, the first electrode 21 is the corresponding electrode with the electrode lead-out structure; similarly, when the electrode lead-out structure is formed on the second electrode 23, the second electrode The electrode 23 is the corresponding electrode of the electrode extraction structure.

Example 4

Embodiment 4 provides a method for manufacturing a thin-film bulk acoustic resonator. FIG. 9 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 in this embodiment. The difference is that the piezoelectric layer 22 in the third embodiment is formed with the first groove 25, and the piezoelectric layer 22 in this embodiment is a complete film layer. The step of etching the piezoelectric layer 22 is omitted. The beneficial effect of the piezoelectric layer 22 being a complete film layer can be referred to in the above-mentioned Embodiment 2, and will not be repeated here.

Example 5

Embodiment 5 of the present invention provides a filter including at least one thin-film bulk acoustic resonator as described above. A filter is formed by connecting the above-mentioned thin film bulk acoustic wave resonators to ensure that the filter has good structural stability, and because the electrode impedance of the resonator is low, the conductivity of the filter can be improved, and the filtering accuracy can be improved.

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. . In particular, for the structural embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and reference may be made to the partial descriptions of the method embodiments for related parts.

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 method for manufacturing a thin-film bulk acoustic resonator, comprising: forming a first substrate with a first sacrificial layer; forming a first electrode, forming a piezoelectric layer, and forming a first electrode on the first substrate in sequence Two electrodes, the first electrode covers the first sacrificial layer; an annular groove is formed on at least one of the first electrode and the second electrode; the annular groove is formed on the corresponding electrode; An electrode lead-out structure with an arched bridge structure is formed on the corresponding electrode of the device, and the arched bridge structure is opposite to the annular groove; the first sacrificial layer is removed to form a first cavity.
The method for manufacturing a thin film bulk acoustic resonator according to claim 1, wherein the method for forming an electrode lead-out structure having an arch bridge structure on the corresponding electrode formed with the annular groove comprises: The method for forming an electrode lead-out structure with an arched bridge structure on the first electrode of the annular trench includes: before forming the first electrode, forming the electrode with the arched bridge structure on the first sacrificial layer a lead-out structure, the electrode lead-out structure extends from the periphery of the effective resonance region to the first substrate on the periphery of the first sacrificial layer; and/or, on the second electrode formed in the annular groove The method for forming the electrode lead-out structure with the arched bridge structure on the electrode comprises: after forming the second electrode, forming the electrode lead-out structure with the arched bridge structure on the second electrode, and the electrode lead-out structure is formed on the second electrode. The structure extends from the periphery of the effective resonance region to the first substrate on the periphery of the first sacrificial layer.
The method for manufacturing a thin film bulk acoustic resonator according to claim 2, wherein the method for forming the electrode lead-out structure with an arch bridge structure on the first sacrificial layer comprises: on the first sacrificial layer. A first groove is formed on a sacrificial layer, and the first groove is located around the effective resonance area; a second groove is formed in the first groove, and the depth of the second groove is greater than that of the first groove the depth of the groove, and the second groove is located at the edge of the effective resonance area; the electrode lead-out structure is formed in the first groove, and the electrode lead-out structure fills up the area other than the second groove. the first groove; a first annular sacrificial protrusion is formed on the electrode lead-out structure located in the second groove; a first electrode is formed on the first substrate, covering the first sacrificial layer, the first sacrificial protrusion and the electrode lead-out structure; the first electrode is etched to form an annular groove; the first annular sacrificial protrusion is removed to form the annular gap.
The method for manufacturing a thin-film bulk acoustic resonator according to claim 3, wherein the second groove encloses a closed ring.
The method for manufacturing a thin film bulk acoustic resonator according to claim 2, wherein the method for forming the electrode lead-out structure with the arched bridge structure on the second electrode comprises: etching the The second electrode forms an annular groove, and the annular groove is located within the range of the first sacrificial layer; the annular groove is filled to form a second annular sacrificial protrusion, and the second annular sacrificial protrusion covers the annular the second electrode in the peripheral region of the trench; an electrode lead-out structure is formed on the second electrode, covering the second annular sacrificial protrusion and extending to the first substrate on the periphery of the first sacrificial layer on the top, the electrode lead-out structure covers at least part of the second electrode located in the effective resonance area; the second annular sacrificial protrusion is removed to form an annular gap and an annular groove.
The method for manufacturing a thin film bulk acoustic wave resonator according to claim 2, wherein the periphery of the first electrode and/or the second electrode extends to the first lining on the periphery of the first sacrificial layer bottom.
The method for manufacturing a thin-film bulk acoustic wave resonator according to claim 1, wherein one of the first electrode and the second electrode is provided with an electrode lead-out structure, and the electrode lead-out structure is not provided with the electrode lead-out structure. Corresponding electrodes of the electrode extraction structure respectively have a first portion extending outside the effective resonance region, and the first portion serves as an electrode connection terminal.
The method for manufacturing a thin-film bulk acoustic resonator according to claim 7, characterized in that when forming the electrode lead-out structure, it further comprises patterning the electrode lead-out structure, and when forming the corresponding electrode lead-out structure without the electrode lead-out structure The electrode process also includes patterning the corresponding electrodes, so that the electrode lead-out structures and the corresponding electrodes without the electrode lead-out structures are at least partially staggered at the periphery of the arch bridge structure.
The method for manufacturing a thin-film bulk acoustic resonator according to claim 1, wherein the first electrode and the second electrode both form an electrode lead-out structure, and the electrode lead-out structure disposed on the first electrode and The electrode lead-out structures disposed on the second electrodes respectively have second portions extending outside the effective resonance region, and the second portions serve as electrode connection terminals.
The method for manufacturing a thin-film bulk acoustic resonator according to claim 9, wherein when forming the electrode lead-out structure, the method further comprises patterning the electrode lead-out structure, so that the electrodes formed on the first electrodes The lead-out structure and the electrode lead-out structure formed on the second electrode are at least partially offset from each other on the periphery of the annular space; the arch bridge structure of the electrode lead-out structure formed on the first electrode is different from the arch bridge structure formed on the first electrode. The arch bridge structures of the electrode lead-out structures on the two electrodes are arranged opposite to each other.
The method for manufacturing a thin film bulk acoustic resonator according to claim 1, wherein the impedance of the electrode extraction structure is lower than the impedance of the corresponding electrode.
The method for manufacturing a thin-film bulk acoustic wave resonator according to claim 1, wherein the material of the electrode extraction structure is a metal material, and the metal material comprises gold, silver, tungsten, platinum, aluminum, copper, titanium, tin, One or more of nickel.
The method for manufacturing a thin-film bulk acoustic resonator according to any one of claims 3 or 5, wherein the annular space is a closed annular space.
The method for manufacturing a thin film bulk acoustic resonator according to claim 1, wherein the piezoelectric layer formed covers the first cavity and extends to the periphery of the first cavity; or, the piezoelectric layer is formed After layering, the piezoelectric layer is etched to form a first trench penetrating the piezoelectric layer, and the first trench is opposite to the annular trench.
The method for manufacturing a thin film bulk acoustic wave resonator according to claim 14, wherein the first groove is a closed ring shape, the piezoelectric layer surrounding the annular space and the piezoelectric layer surrounding the annular space The layers are isolated from each other; or, the first groove is an interrupted annular shape, and the piezoelectric layer around the annular gap is isolated from the piezoelectric layer around the annular gap through the discontinuity.
The method for manufacturing a thin film bulk acoustic resonator according to claim 1, wherein the first substrate comprises a support layer and a base, and the method for forming the first substrate having the first sacrificial layer comprises: providing the substrate; forming a support layer on the substrate; patterning the support layer to form a first cavity; filling the first cavity to form a first sacrificial layer, the first surface of the first sacrificial layer flush with the first surface of the support layer.
The method for manufacturing a thin film bulk acoustic resonator according to claim 16, wherein the first cavity extends to a part of the thickness of the support layer; or, the first cavity penetrates through the support layer.
The method for manufacturing a thin film bulk acoustic wave resonator according to claim 1, wherein the material of the first sacrificial layer comprises phosphosilicate glass, low temperature silicon dioxide, borophosphosilicate glass, germanium, amorphous carbon, polysilicate imide or photoresist.
The method for manufacturing a thin-film bulk acoustic 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 A combination of one or more of , iridium, chromium, titanium, gold, osmium, rhenium or palladium.
The method for manufacturing a thin-film bulk acoustic resonator according to claim 1, wherein the piezoelectric layer is made of materials including: aluminum nitride, zinc oxide, lead zirconate titanate, lithium niobate, quartz, potassium niobate or lithium tantalate.
A filter is characterized by comprising at least one thin-film bulk acoustic resonator formed by the method for manufacturing a thin-film bulk acoustic resonator according to any one of claims 1-20.