CN115051679A

CN115051679A - Resonator, method of manufacturing the same, filter, and electronic apparatus

Info

Publication number: CN115051679A
Application number: CN202110248359.0A
Authority: CN
Inventors: 张巍; 庞慰; 郝龙
Original assignee: ROFS Microsystem Tianjin Co Ltd
Current assignee: ROFS Microsystem Tianjin Co Ltd
Priority date: 2021-03-08
Filing date: 2021-03-08
Publication date: 2022-09-13
Also published as: WO2022188779A1

Abstract

The invention relates to a resonator and a method of manufacturing the same. The resonator includes: a substrate; an acoustic mirror; a resonant structure comprising a single crystal piezoelectric layer and an electrode layer, the piezoelectric layer being arranged substantially parallel to a substrate; a support structure disposed between the substrate and the resonant structure, wherein: the support structure defines at least a portion of a boundary of the acoustic mirror in a horizontal direction; the upper surface of the support structure is a flat surface. The invention also relates to a filter and an electronic device.

Description

Resonator, method of manufacturing the same, filter, and electronic apparatus

Technical Field

Embodiments of the present invention relate to the field of semiconductors, and in particular, to a resonator, a method of manufacturing the same, a filter having the same, and an electronic device.

Background

Electronic devices have been widely used as basic elements of electronic equipment, and their application range includes mobile phones, automobiles, home electric appliances, and the like. In addition, technologies such as artificial intelligence, internet of things, 5G communication and the like which will change the world in the future still need to rely on electronic devices as a foundation.

Film Bulk Acoustic Resonator (FBAR, also called Bulk Acoustic Resonator, BAW for short) is playing an important role in the communication field as an important member of piezoelectric devices, especially FBAR filters have increasingly large market share in the field of radio frequency filters, FBARs have excellent characteristics of small size, high resonance frequency, high quality factor, large power capacity, good roll-off effect and the like, the filters gradually replace traditional Surface Acoustic Wave (SAW) filters and ceramic filters, play a great role in the radio frequency field of wireless communication, and the advantage of high sensitivity can also be applied to the sensing fields of biology, physics, medicine and the like.

The structural main body of the film bulk acoustic resonator is a sandwich structure consisting of a bottom electrode, a piezoelectric film or a piezoelectric layer and a top electrode, namely a layer of piezoelectric material is sandwiched between two metal electrode layers. By inputting a sinusoidal signal between the two electrodes, the FBAR converts the input electrical signal into mechanical resonance using the inverse piezoelectric effect, and converts the mechanical resonance into an electrical signal for output using the piezoelectric effect.

Due to the limitations of the manufacturing process, for example, the existence of the non-electrode connecting end of the bottom electrode, the piezoelectric layer of the bulk acoustic wave resonator is not a flat structure, which is not favorable for improving the performance of the resonator.

The prior art has proposed that the piezoelectric layer is a single crystal piezoelectric layer having a flat characteristic, so that the problem caused by the presence of the stepped portion of the piezoelectric layer can be overcome.

FBAR, lateral vibration resonator devices, have high quality requirements for piezoelectric materials. The traditional process needs to consider the surface characteristics of the piezoelectric material before growth, such as flatness, crystal direction and the like, which needs very strict process control, and the processing difficulty is very high.

Some piezoelectric materials cannot be grown on the device by deposition, or have great process difficulty, such as LiNbO ₃ ，LiTaO ₃ And so on. It is currently common to grow a whole column of crystals, followed by a specific orientation cut, followed by a specific available thickness of material attached to a temporary substrate.

However, how to effectively transfer the piezoelectric material on the temporary substrate to the FBAR or lateral vibration resonator device is a technical problem to be solved in the prior art.

Disclosure of Invention

The present invention has been made to mitigate or solve at least one of the above-mentioned problems in the prior art.

According to an aspect of an embodiment of the present invention, there is provided a resonator including:

a substrate;

an acoustic mirror;

a resonant structure comprising a single crystal piezoelectric layer and an electrode layer, the piezoelectric layer being arranged substantially parallel to a substrate;

a support structure disposed between the substrate and the resonant structure,

wherein:

the support structure defines at least a portion of a boundary of the acoustic mirror in a horizontal direction;

the upper surface of the support structure is a flat surface.

The invention also relates to a method for manufacturing a resonator comprising a substrate; an acoustic mirror; a resonant structure comprising a single crystal piezoelectric layer and an electrode layer, the piezoelectric layer being arranged substantially parallel to a substrate; a support structure disposed between the substrate and the resonant structure, the method comprising:

forming a flat layer of support material on a flat layer;

patterning the layer of support material to form a cavity for an acoustic mirror, thereby forming a support structure having an upper surface with a first planar face and a lower surface with a second planar face; and

bonding a substrate to the support structure at the second planar surface.

Embodiments of the invention also relate to a filter comprising a resonator as described above.

Embodiments of the invention also relate to an electronic device comprising a filter as described above or a resonator as described above.

Drawings

These and other features and advantages of the various embodiments of the disclosed invention will be better understood from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate like parts throughout, and in which:

fig. 1, 2A and 2B are a schematic top view, a schematic cross-sectional view along line AA 'in fig. 1, and a schematic cross-sectional view along line BB' in fig. 1, respectively, of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention;

3-14 are a series of diagrams illustrating a fabrication process of the bulk acoustic wave resonator shown in FIG. 2A;

figures 15-17 are schematic cross-sectional views of a bulk acoustic wave resonator similar to that taken along line BB' in figure 1, according to further different exemplary embodiments of the present invention;

fig. 18A and 18B are a schematic top view and a schematic cross-sectional view, respectively, of a laterally vibrating resonator according to an exemplary embodiment of the present invention;

fig. 19 to 26 are series diagrams exemplarily showing a process of manufacturing the lateral vibration resonator shown in fig. 18B;

fig. 27-29 are schematic cross-sectional views of a laterally vibrating resonator according to further various exemplary embodiments of the present invention.

Detailed Description

The technical scheme of the invention is further specifically described by the following embodiments and the accompanying drawings. In the specification, the same or similar reference numerals denote the same or similar components. The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the general inventive concept of the present invention and should not be construed as limiting the invention. Some, but not all embodiments of the invention are described. All other embodiments that can be derived by one of ordinary skill in the art from the embodiments given herein are intended to be within the scope of the present invention.

Embodiments of the present invention are specifically described below with reference to fig. 1 to 29.

The reference numbers in the figures of the present invention are exemplary as follows:

100: the substrate is made of silicon, silicon carbide, sapphire, silicon dioxide or other silicon-based materials.

101: a single crystal piezoelectric layer, which may be a single crystal aluminum nitride, a single crystal gallium nitride, a single crystal lithium niobate, a single crystal lead zirconate titanate, a single crystal potassium niobate, a single crystal quartz film, or a single crystal lithium tantalate, and may further include a rare earth element-doped material in an atomic ratio of the above-mentioned material, for example, a doped aluminum nitride, which contains at least one rare earth element, such as scandium (Sc), yttrium (Y), magnesium (Mg), titanium (Ti), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), and the like.

102: the bottom electrode (electrode pin) is made of molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or a composite of the above metals or an alloy thereof.

103: the material of the supporting layer or the bonding layer can be aluminum nitride, silicon nitride, polysilicon, silicon dioxide, amorphous silicon, boron-doped silicon dioxide and other silicon-based materials, gold, copper and the like.

1030: the acoustic mirror can be a cavity, and a Bragg reflection layer and other equivalent forms can also be adopted. The illustrated embodiment of the invention utilizes a cavity.

104: the top electrode (electrode pin) is made of molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or a composite of the above metals or an alloy thereof. The material of the top electrode may be the same as or different from the material of the bottom electrode.

105: the passivation layer is typically a dielectric material such as silicon dioxide, aluminum nitride, silicon nitride, etc.

106: the electrical isolation layer or the insulating layer may be made of non-conductive materials such as silicon oxide, silicon nitride, silicon carbide, etc.

107: the metal pad or the electrode connecting portion may be made of a material having high electrical conductivity, such as gold, copper, or aluminum.

108: the top electrode leading-out part is made of the same material as the top electrode;

200: the auxiliary substrate or the temporary substrate may be silicon, silicon carbide, sapphire, silicon dioxide, or other silicon-based materials.

201: insulating layers of materials such as silicon dioxide, silicon nitride, silicon carbide, sapphire, and the like.

Fig. 1, 2A and 2B are a schematic top view, a schematic cross-sectional view along line AA in fig. 1, and a schematic cross-sectional view along line BB in fig. 1, respectively, of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention.

As shown in fig. 1, 2A and 2B, the bulk acoustic wave resonator includes: the piezoelectric element comprises a substrate 100, a piezoelectric layer 101, a bottom electrode 102, a support layer 103, a top electrode 104, an acoustic mirror 1030, a passivation layer 105, an electrical isolation layer 106, an electrode connection portion 107 respectively connected with an electrical connection end of the bottom electrode and an electrical connection end of the top electrode, and a top electrode lead-out portion 108. In the bulk acoustic wave resonator, the top electrode, the piezoelectric layer, and the bottom electrode constitute a resonance structure.

As shown in fig. 2A and 2B, the bottom electrode 102 is disposed on the upper surface of the support layer 103, the bottom electrode 102 is a flat electrode, and the lower surface of the bottom electrode 102 defines the lower surface of the resonant structure facing the support layer 103.

As will be mentioned later with reference to fig. 3 to 14, the support layer 103 is a flat layer, the bottom electrode 102 is also a flat layer, the support layer 103 is formed on the flat layer of the unpatterned bottom electrode 102, and the upper surface of the support layer 103 in fig. 2A is a flat surface (i.e., a first flat surface) so that the lower surface of the support layer 103 is directly a flat surface (a second flat surface), so that the lower surface of the support layer 103 does not need an additional process such as CMP (chemical mechanical polishing) to planarize the lower surface of the support layer. In this way, the lower surface of the support layer 103 is subjected to only one patterning step, so that the surface characteristics thereof are good, and the bonding connection of the lower surface of the support layer 103 and the substrate 100 is facilitated.

It is noted that in the present invention, the fact that the upper surface of the support structure or support layer (i.e., the surface away from the substrate 100) is a flat surface means that the upper surface of the portion of the support structure or support layer other than the etched or removed portion is a flat surface.

Since the upper surface of the support structure or the support layer is a flat surface, in the present invention, the upper surface and the lower surface of the support structure or the support layer are horizontal surfaces parallel to each other.

In one embodiment of the present invention, as shown in fig. 2A, an insulating layer 106 is disposed between the electrical connection terminal of the top electrode 104 and the end surface of the piezoelectric layer 101, the insulating layer 106 electrically isolating the electrical connection terminal of the top electrode 104 from the bottom electrode 102.

In one embodiment of the present invention, as shown in fig. 2A, the resonator further includes a top electrode lead-out 108 disposed at the same layer as the bottom electrode 102, and the electrode connection end of the top electrode 104 is electrically connected to the top electrode lead-out 108.

In one embodiment of the present invention, as shown in fig. 2A and 2B, the support layer 103 defines the boundary of the acoustic mirror 1030 in the horizontal direction, and the lower surface of the bottom electrode 102 defines the upper boundary of the acoustic mirror 1030.

The following is an exemplary description of the fabrication process of the bulk acoustic wave resonator shown in fig. 2A with reference to fig. 3-14.

As shown in fig. 3, a POI (single crystal piezoelectric layer on Insulator) wafer is shown. As shown in fig. 3, the POI wafer includes an auxiliary substrate 200, an insulating layer 201, and a single crystal piezoelectric layer 101, which may be a piezoelectric single crystal thin film of lithium niobate, lithium tantalate, quartz, or the like, as already mentioned above.

The crystal orientation of the piezoelectric single crystal thin film in the POI wafer is various and is not limited by the growth conditions of the piezoelectric thin film, so that the piezoelectric single crystal thin film with special crystal orientation can be selected according to the needs to manufacture resonators and filters with various performances.

As mentioned later, the insulating layer 201 can better protect the single crystal piezoelectric film (i.e. the single crystal piezoelectric layer) during the resonator transfer process, so that the damage to the single crystal piezoelectric film during the subsequent process of removing the auxiliary substrate can be reduced or even avoided, and the surface damage to the piezoelectric film can be reduced or even avoided, so as to obtain the bulk acoustic wave resonator with excellent performance.

In addition, the existence of the insulating layer 201 is beneficial to separating the piezoelectric layer 101 from the auxiliary substrate 200, is beneficial to diversification of an auxiliary substrate removing scheme, and simplifies the device processing technology.

It is noted that in one embodiment of the present invention, instead of using a POI wafer, the auxiliary substrate 200 and the single crystal piezoelectric layer 101 disposed on the auxiliary substrate 200 may be directly provided.

Fig. 4 exemplarily shows that a bottom electrode film layer for forming the bottom electrode 102 is deposited or grown on the surface of the piezoelectric single crystal thin film. Obviously, the surface of the bottom electrode film layer is a flat and flat surface.

Fig. 5 shows that a layer of support material or a layer of bonding material corresponding to the support layer 103 is deposited on the bottom electrode film layer. Obviously, due to the support material layer formed on the flat bottom electrode film layer, the upper surface of the support material layer in fig. 5 is also a flat surface, which may have a flatness of less than 2nm, for example, and does not require a so-called polishing process (such as CMP) to planarize the surface thereof.

Fig. 6 shows patterning of the layer of support material by means of, for example, wet or dry etching, to form the support layer 103, and to form a cavity for forming the acoustic mirror 1030. As can be appreciated, the cavity may constitute an acoustic mirror cavity, and a bragg reflector layer may be disposed therein to form other types of acoustic mirror structures.

Fig. 7 shows the structure after bonding of the support layer 103 with the substrate 100. The substrate 100 and the support layer 103 may be bonded by a physical or chemical manner, a chemical bond may be formed between the substrate 100 and the support layer 103, or a physical bond may be formed by intermolecular force. For example, if the support layer 103 is silicon oxide and the substrate 100 is silicon, "direct bonding" may be used. At this time, the support layer 103 grows on the non-patterned surface and undergoes only one-step etching, so that the surface characteristics are good and a good bonding effect can be achieved.

Although not shown, a special bonding material layer may also be provided, which is provided between the support layer 103 and the substrate 100 for bonding. The bonding material layer may be on the substrate 100 or the support layer 103 alone, or on both surfaces.

In the present invention, the support structure disposed between the resonant structure and the substrate may be only the support layer 103, or may include the support layer 103 and a bonding material layer disposed additionally or other functional layers that do not affect the bonding connection between the resonant structure and the substrate.

Fig. 8 shows the structure of the device shown in fig. 7 inverted and the substrate 200 removed. Fig. 9 shows the structure of fig. 8 after the insulating layer 201 is removed.

The etching processes of the auxiliary substrate 200 and the insulating layer 201 (barrier layer) are different, for example, the auxiliary substrate 200 is silicon, the insulating layer 201 is silicon dioxide, the insulating layer 201 can function as a stop layer or a barrier layer in the process of removing the auxiliary substrate 100, the removing process of the insulating layer 201 is mild, and damage to the other surface of the piezoelectric single crystal thin film in the process of removing the auxiliary substrate 200 is reduced or even avoided.

The piezoelectric single crystal thin film surface release process can be realized by completely removing the substrate 200 and the insulating layer 201.

In an alternative embodiment, the steps shown in fig. 8 and 9 may also be: due to the existence of the insulating layer 201 as a barrier layer, the piezoelectric single crystal thin film surface release process may employ first forming release holes on the substrate 200 and then releasing the insulating layer material through the release holes. If the process of forming the release holes on the substrate 200 does not cause any damage to the insulating layer 201 and the single crystal piezoelectric layer 101, the release holes can be arranged in any region; if the insulating layer 201 and the single crystal piezoelectric layer 101 are damaged, a release hole can be formed in an out-of-band area (such as a scribe lane) of the resonator or a filter formed by the resonator, so that the device processing process is simple.

The process of assisting the overall removal of the substrate 200 or forming the release hole may employ a related process such as grinding, lapping, polishing, or a combination thereof.

The overall removal process of the insulating layer 201 may adopt related processes such as grinding, lapping, polishing, wet or dry etching, or a combination of these processes.

After the insulating layer 201 is removed, if the surface of the piezoelectric single crystal thin film has partial damage, especially damage to the effective region of the resonator or the filter formed by the resonator, the surface of the piezoelectric thin film may be polished by a polishing process.

In the case where the insulating layer 201 is not provided, the step shown in fig. 9 may be omitted.

Based on the steps shown in fig. 3-9, a piezoelectric layer transfer process is implemented.

Fig. 10 shows a structure in which the piezoelectric film layer in the structure shown in fig. 9 is patterned to form a piezoelectric layer 101.

Fig. 11 shows a structure based on the structure shown in fig. 10, followed by patterning the bottom electrode film layer by, for example, wet or dry etching to form the bottom electrode 102 and the top electrode lead-out portion 108. It is apparent that the piezoelectric layer 101 covers only a portion of the bottom electrode 102 as shown in fig. 11 because the piezoelectric layer 101 constitutes a barrier layer during etching or patterning of the bottom electrode film layer.

As shown in fig. 12A, a layer of isolation material is formed on the structure shown in fig. 11, and covers at least the piezoelectric layer 101 and the bottom electrode 102. Referring to fig. 12, the isolation material layer includes an insulating layer 106 covering the end face of the piezoelectric layer 101 and the end face of the non-electric connection terminal of the bottom electrode. The layer of isolating material is a layer of electrically insulating material.

As shown in fig. 12B, the spacer material layer in fig. 12A is patterned, leaving the insulating layer 106.

As shown in fig. 13, a top electrode film layer is formed and patterned on the structure shown in fig. 12B to form the top electrode 104 and an electrical connection portion of the top electrode, which obviously covers the insulating layer 106 and is connected to the top electrode lead-out portion 108.

In the embodiment shown in fig. 13, functional layers such as the passivation layer 105 are shown, as can be appreciated, the passivation layer 105 or other functional layers may not be provided.

As shown in fig. 14, an electrode connection portion or an external lead 107 is provided on the structure shown in fig. 13, thereby forming a resonator structure as shown in fig. 2A.

In the embodiment shown in fig. 2A-2B, the upper interface of the acoustic mirror 1030 is defined by the lower surface of the bottom electrode 102, although the invention is not limited thereto.

Fig. 15 is a schematic cross-sectional view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention, similar to along the line BB in fig. 1. As shown in fig. 15, the upper interface of the acoustic mirror 1030 may also be defined by the support layer 103, i.e., there is also a layer 1031 of support material between the acoustic mirror 1030 and the bottom electrode 102 in the thickness direction of the piezoelectric layer. Otherwise, the embodiment shown in FIG. 15 is identical to the structure shown in FIGS. 2A-2B and will not be described again.

The supporting material layer 1031 in fig. 15 may have various functions, for example, in the case that the supporting material is silicon oxide, it may function as a temperature compensation layer, for example, in the case that the supporting material is a material with good thermal conductivity such as diamond and silicone grease, it may be beneficial to dissipate heat so as to improve the power capacity of the resonator.

Fig. 16 is a schematic cross-sectional view, similar to line BB in fig. 1, of a bulk acoustic wave resonator according to an exemplary embodiment of the invention. The difference between the structure shown in fig. 16 and the structure shown in fig. 15 is that in fig. 16, a functional layer 1032 is further provided in contact with the support material layer 1031, and the functional layer 1032 may be a material having a negative temperature coefficient such as silicon oxide, a highly heat conductive material such as molybdenum, tungsten, or copper, or another acoustic material used in cooperation with the support material layer 1031.

Fig. 17 is a schematic cross-sectional view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention, similar to along the line BB in fig. 1. The structure of fig. 17 differs from the structure shown in fig. 2B in that, in fig. 17, a functional layer 1033 in contact with the bottom electrode 102 and a functional layer 1032 in contact with the functional layer 1033 are further provided, and the material of the functional layer 1033 is different from that of the support layer 103. The functional layer 1032 may be a material with a negative temperature coefficient, such as silicon oxide, and may be a high thermal conductive material, such as molybdenum, tungsten, or copper, and the functional layer 1033 may be a material with a negative temperature coefficient, such as silicon oxide, and may be a high thermal conductive material, such as molybdenum, tungsten, or copper, and may also be another acoustic material used in cooperation with the functional layer 1032.

In the invention, the support material layer 1031, the functional layer 1032 and the functional layer 1033 can also be used as an acoustic reflection layer in a matching manner, so that the leakage of sound waves is limited, and the Q value of FABR is improved.

The fabrication process for the structure shown in fig. 15-17 is similar to that of the structure shown in fig. 2B, except that for the structure shown in fig. 15, the cavity formed does not reach the bottom electrode film layer in the step shown in fig. 6, for the structure shown in fig. 16, a step of forming a functional layer 1032 in the cavity is further included after the step shown in fig. 6, relative to the structure shown in fig. 15, and for the structure shown in fig. 17, a step of disposing the

functional layers

1033 and 1032 is further included after the step shown in fig. 6. Other steps are the same as or similar to the manufacturing process of the structure shown in fig. 2B, and are not described again here.

In the embodiments shown in fig. 1-17, the resonators are bulk acoustic wave resonators, but the invention is also applicable to laterally vibrating resonators.

Fig. 18A and 18B are a schematic top view and a schematic cross-sectional view, respectively, of a laterally vibrating resonator according to an exemplary embodiment of the present invention.

As shown in fig. 18A and 18B, the lateral vibration resonator includes

interdigital electrodes

301 and 302 provided on the upper surface of the piezoelectric layer 101. Further, as shown in fig. 18B, the lower surface of the piezoelectric layer 101 defines a flat surface bonded to the support layer 103.

A process of fabricating the lateral vibration resonator shown in fig. 18B will be described as an example with reference to fig. 19 to 26.

As shown in fig. 19, a POI wafer is shown. This is similar to the description above with reference to fig. 3 and will not be described again here.

As shown in fig. 20, a support material layer or a bonding material layer corresponding to the support layer 103 is deposited directly on the piezoelectric film layer. Obviously, due to the support material layer formed on the flat piezoelectric film layer, the surface of the support material layer is also a flat surface, the flatness of the flat surface can be less than 2nm, and a so-called polishing process (such as CMP) is not required to planarize the surface thereof.

Fig. 21 shows patterning of the layer of support material by means of, for example, wet or dry etching, to form the support layer 103, and to form a cavity for forming the acoustic mirror 1030. As can be appreciated, the cavity may constitute an acoustic mirror cavity, in which a bragg reflector layer may also be provided to form other types of acoustic mirror structures.

Fig. 22 shows a structure after bonding of the support layer 103 and the base 100, fig. 23 shows a structure after inverting the device shown in fig. 22 and removing the substrate 200, and fig. 24 shows a structure after removing the insulating layer 201 in fig. 23. This is similar to that described above with reference to fig. 7-9 and will not be described again here.

Fig. 25 shows a structure in which the piezoelectric film layer in the structure shown in fig. 24 is patterned to form a piezoelectric layer 101.

Fig. 26 shows a step of forming

interdigital electrodes

301 and 302 on the upper surface of the piezoelectric layer 101 of the structure shown in fig. 25, thereby obtaining the structure shown in fig. 18B.

In the embodiment shown in fig. 18A-26, the upper interface of the acoustic mirror 1030 is defined by the lower surface of the bottom electrode 102, although the invention is not so limited.

Fig. 27 is a schematic cross-sectional view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention. As shown in fig. 27, the upper interface of the acoustic mirror 1030 may also be defined by a support layer 103, i.e. there is also a layer 1031 of support material between the acoustic mirror 1030 and the bottom electrode 102 in the thickness direction of the piezoelectric layer. Otherwise, the embodiment shown in fig. 27 is the same as the structure shown in fig. 18B, and will not be described again here.

The supporting material layer 1031 in fig. 27 may have various functions, for example, in the case that the supporting material is silicon oxide, it may function as a temperature compensation layer, for example, in the case that the supporting material is a material with good thermal conductivity such as diamond and silicone grease, it may be beneficial to dissipate heat so as to improve the power capacity of the resonator.

Fig. 28 is a schematic cross-sectional view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention. The difference between the structure of fig. 28 and the structure shown in fig. 27 is that in fig. 28, a functional layer 1032 is further provided in contact with the support material layer 1031, and the functional layer 1032 may be a material having a negative temperature coefficient such as silicon oxide, a highly heat conductive material such as molybdenum, tungsten, or copper, or another acoustic material used in cooperation with the support material layer 1031.

Fig. 29 is a schematic cross-sectional view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention. The structure of fig. 29 differs from the structure shown in fig. 18B in that, in fig. 29, a functional layer 1033 in contact with the bottom electrode 102 and a functional layer 1032 in contact with the functional layer 1033 are further provided, and the material of the functional layer 1033 is different from that of the support layer 103. The functional layer 1032 may be a material with a negative temperature coefficient, such as silicon oxide, and may be a high thermal conductive material, such as molybdenum, tungsten, or copper, and the functional layer 1033 may be a material with a negative temperature coefficient, such as silicon oxide, and may be a high thermal conductive material, such as molybdenum, tungsten, or copper, and may also be another acoustic material used in cooperation with the functional layer 1032.

In the invention, the support material layer 1031, the functional layer 1032 and the functional layer 1033 can also be used as an acoustic reflection layer in a matching manner, so that acoustic wave leakage is limited, and the Q value of the XABR is improved.

The fabrication process for the structure shown in fig. 27-29 is similar to that of the structure shown in fig. 18B, except that for the structure shown in fig. 27, the cavity formed does not reach the bottom electrode film layer in the step shown in fig. 21, for the structure shown in fig. 28, a step of forming a functional layer 1032 in the cavity is further included after the step shown in fig. 21 with respect to the structure shown in fig. 27, and for the structure shown in fig. 29, a step of disposing the

functional layers

1033 and 1032 is further included after the step shown in fig. 21. Other steps are the same as or similar to the manufacturing process of the structure shown in fig. 18B, and are not described again here.

In the present invention, the upper and lower are with respect to the bottom surface of the base of the resonator, and with respect to one component, the side thereof close to the bottom surface is the lower side, and the side thereof far from the bottom surface is the upper side.

In the present invention, the inner and outer are in the lateral direction or the radial direction with respect to the center of the effective area (i.e., the effective area center) of the resonator (the overlapping area of the piezoelectric layer, the top electrode, the bottom electrode, and the acoustic mirror in the thickness direction of the resonator constitutes the effective area), the side or end of a member close to the effective area center is the inner side or the inner end, and the side or end of the member away from the effective area center is the outer side or the outer end. For a reference position, inboard of the position means between the position and the center of the active area in the lateral or radial direction, and outboard of the position means farther from the center of the active area in the lateral or radial direction than the position.

As can be appreciated by those skilled in the art, the bulk acoustic wave resonator according to the present invention may be used to form a filter or an electronic device.

Based on the above, the invention provides the following technical scheme:

1. a resonator, comprising:

a substrate;

an acoustic mirror;

a support structure disposed between the substrate and the resonant structure,

wherein:

the upper surface of the support structure is a flat surface.

2. The resonator of claim 1, wherein:

the resonator is a bulk acoustic wave resonator, and the electrode layer comprises a top electrode and a bottom electrode which are respectively arranged on two sides of the piezoelectric layer;

the bottom electrode is arranged on the upper surface of the supporting structure, the bottom electrode is a flat electrode, and the lower surface of the bottom electrode defines the surface of the resonant structure facing the flat surface.

3. The resonator of claim 2, wherein:

an insulating layer is arranged between the electric connection end of the top electrode and the end face of the piezoelectric layer, and the electric connection end of the top electrode is electrically isolated from the bottom electrode by the insulating layer.

4. The resonator of claim 3, wherein:

the resonator further comprises a top electrode leading-out part arranged on the same layer as the bottom electrode, and the electrode connecting end of the top electrode is electrically connected with the top electrode leading-out part.

5. The resonator of claim 2, wherein:

the bottom electrode defines at least a portion of an upper surface of the acoustic mirror; or

The support structure defines at least a portion of an upper surface of the acoustic mirror.

6. The resonator of claim 1, wherein:

the resonator is a transverse vibration resonator, and the electrode layer comprises an interdigital electrode arranged on the upper surface of the piezoelectric layer;

the lower surface of the piezoelectric layer defines a surface of the resonant structure facing the planar face.

7. The resonator of claim 1, wherein:

the top of the acoustic mirror is further provided with at least one functional layer, and the material of the functional layer is different from that of the support structure.

8. The resonator of claim 7, wherein:

the at least one functional layer comprises at least one of a temperature compensation layer, a heat conduction material layer and an acoustic material layer.

9. The resonator of claim 1, wherein:

the lower surface of the resonance structure and a portion of the upper surface of the support structure facing each other are brought into surface contact.

10. The resonator of any of claims 1-9, wherein:

the piezoelectric layer is a lithium niobate piezoelectric layer or a lithium tantalate piezoelectric layer.

11. A method of manufacturing a resonator, the resonator comprising a substrate; an acoustic mirror; a resonant structure comprising a single crystal piezoelectric layer and an electrode layer, the piezoelectric layer being arranged substantially parallel to a substrate; a support structure disposed between the substrate and the resonant structure, the method comprising:

forming a flat layer of support material on a flat layer;

bonding a substrate to the support structure at the second planar surface.

12. The method of claim 11, wherein:

the resonator is a bulk acoustic wave resonator, the electrode layer comprises a top electrode and a bottom electrode which are respectively arranged on two sides of the piezoelectric layer, and the method comprises the following steps:

step 1: providing a substrate and a single crystal piezoelectric layer disposed on the substrate;

step 2: forming a flat layer of bottom electrode material on a second side of the piezoelectric layer opposite the first side;

and step 3: forming a flat support material layer on the bottom electrode material layer, wherein the upper surface of the support material layer is provided with a first flat surface, the lower surface of the support material layer is provided with a second flat surface, and the bottom electrode material layer forms the flat layer;

and 4, step 4: patterning the layer of support material to form a cavity for the acoustic mirror, thereby forming a support structure;

and 5: bonding a substrate to the support structure at the second planar face;

step 6: removing the substrate to expose a first side of the piezoelectric layer;

and 7: patterning the piezoelectric layer;

and 8: patterning the bottom electrode material layer to form a bottom electrode;

and step 9: a top electrode is disposed on the first side of the piezoelectric layer.

13. The method of claim 12, wherein:

the step 1 comprises the following steps: providing a POI wafer comprising a substrate, a single crystal piezoelectric layer, and an insulating layer disposed between a first side of the single crystal piezoelectric layer and the substrate;

the step 2 comprises the following steps: forming a flat layer of bottom electrode material on a second side of the piezoelectric layer of the POI wafer opposite the first side;

the step 6 comprises the following steps: the substrate and part or all of the insulating layer are removed, at least a portion of the insulating layer is removed to expose the first side of the piezoelectric layer, and the insulating layer of the first side of the piezoelectric layer corresponding to the active area of the resonator is removed.

14. The method of claim 12, wherein:

step 10 is also included between step 8 and step 9: arranging an insulating layer, wherein the insulating layer at least covers the end face of the piezoelectric layer and the end face of the non-electric connection end of the bottom electrode;

in step 9, the electrical connection end of the top electrode covers at least a portion of the insulating layer.

15. The method of claim 14, wherein:

in step 8, patterning the bottom electrode material layer to simultaneously form a bottom electrode and a top electrode lead-out part;

in step 9, the electrode connection end of the top electrode is electrically connected to the top electrode lead-out portion.

16. The method of claim 11, wherein:

the resonator is a transverse vibration resonator, the electrode layer comprises interdigital electrodes arranged on the upper surface of the piezoelectric layer, and the method comprises the following steps:

and 2, step: forming a flat layer of support material on a second side of the piezoelectric layer opposite the first side, the layer of support material having a flat face, the piezoelectric layer constituting the flat layer;

and 3, step 3: patterning the layer of support material to form a cavity for the acoustic mirror, thereby forming a support structure;

and 4, step 4: bonding a substrate to the support structure at the second planar face;

and 5: removing the substrate to expose a first side of the piezoelectric layer;

step 6: the interdigitated electrodes are disposed on a first side of the piezoelectric layer.

17. The method of claim 16, wherein:

the step 5 comprises the following steps: the substrate and a portion or all of the insulating layer are removed, and at least a portion of the insulating layer is removed to expose the first side of the piezoelectric layer.

18. The method of claim 16, further comprising:

and 7: the piezoelectric layer is patterned.

19. A filter comprising a resonator according to any of claims 1-10.

20. An electronic device comprising a filter according to claim 19, or a resonator according to any of claims 1-10.

The electronic device includes, but is not limited to, intermediate products such as a radio frequency front end and a filtering and amplifying module, and terminal products such as a mobile phone, WIFI and an unmanned aerial vehicle.

Although embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.

Claims

1. A resonator, comprising:

a substrate;

an acoustic mirror;

a support structure disposed between the substrate and the resonant structure,

wherein:

the upper surface of the support structure is a flat surface.

2. The resonator of claim 1, wherein:

3. The resonator of claim 2, wherein:

4. The resonator of claim 3, wherein:

5. The resonator of claim 2, wherein:

6. The resonator of claim 1, wherein:

7. The resonator of claim 1, wherein:

the top of the acoustic mirror is further provided with at least one functional layer, the material of which is different from the material of the support structure.

8. The resonator of claim 7, wherein:

9. The resonator of claim 1, wherein:

10. The resonator of any one of claims 1-9, wherein:

forming a flat layer of support material on a flat layer;

bonding a substrate to the support structure at the second planar surface.

12. The method of claim 11, wherein:

and 3, step 3: forming a flat support material layer on the bottom electrode material layer, wherein the upper surface of the support material layer is provided with a first flat surface, the lower surface of the support material layer is provided with a second flat surface, and the bottom electrode material layer forms the flat layer;

and 5: bonding a substrate to the support structure at the second planar face;

and 7: patterning the piezoelectric layer;

13. The method of claim 12, wherein:

the step 6 comprises the following steps: and removing the substrate and part or all of the insulating layer, wherein at least one part of the insulating layer is removed to expose the first side of the piezoelectric layer, and the insulating layer corresponding to the effective area of the resonator on the first side of the piezoelectric layer is removed.

14. The method of claim 12, wherein:

15. The method of claim 14, wherein:

16. The method of claim 11, wherein:

step 2: forming a flat layer of support material on a second side of the piezoelectric layer opposite the first side, the layer of support material having a flat face, the piezoelectric layer constituting the flat layer;

17. The method of claim 16, wherein:

18. The method of claim 16, further comprising:

and 7: the piezoelectric layer is patterned.

19. A filter comprising a resonator according to any of claims 1-10.