WO2022188779A1

WO2022188779A1 - Resonator and manufacturing method therefor, filter, and electronic device

Info

Publication number: WO2022188779A1
Application number: PCT/CN2022/079748
Authority: WO
Inventors: 张巍; 庞慰; 郝龙
Original assignee: 诺思(天津)微系统有限责任公司
Priority date: 2021-03-08
Filing date: 2022-03-08
Publication date: 2022-09-15
Also published as: CN115051679A

Abstract

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

Description

Resonator and its manufacturing method, filter and electronic equipment

technical field

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

Background technique

As the basic elements of electronic equipment, electronic devices have been widely used, and their applications include mobile phones, automobiles, home appliances and so on. In addition, technologies such as artificial intelligence, the Internet of Things, and 5G communications that will change the world in the future still need to rely on electronic devices as their foundation.

Film Bulk Acoustic Resonator (FBAR, also known as Bulk Acoustic Resonator, also known as BAW) as an important member of piezoelectric devices is playing an important role in the field of communication, especially FBAR filter in radio frequency filter The market share in the field is increasing. FBAR has excellent characteristics such as small size, high resonant frequency, high quality factor, large power capacity, and good roll-off effect. Its filters are gradually replacing traditional surface acoustic wave (SAW) filters And ceramic filters, play a huge role in the field of wireless communication radio frequency, its high sensitivity advantage can also be applied to biological, physical, medical and other sensing fields.

The main structure of the thin film bulk acoustic wave resonator is a "sandwich" structure composed of a bottom electrode-piezoelectric film or a piezoelectric layer-top electrode, that is, a piezoelectric material is sandwiched between two metal electrode layers. By inputting a sinusoidal signal between two electrodes, the FBAR uses the inverse piezoelectric effect to convert the input electrical signal into mechanical resonance, and then uses the piezoelectric effect to convert the mechanical resonance into an electrical signal output.

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 BAW resonator is not a flat structure, which is not conducive to improving the performance of the resonator.

In the prior art, it has been proposed that the piezoelectric layer is a single crystal piezoelectric layer, and the single crystal piezoelectric layer has a flat characteristic, so that the problem caused by the existence of a stepped portion in the piezoelectric layer can be overcome.

FBAR, lateral vibration resonator devices, have high requirements on the quality of piezoelectric materials. The traditional process needs to consider the surface characteristics of piezoelectric materials before growth, such as flatness, crystal orientation, etc., which requires very strict process control and is very difficult to process.

Some piezoelectric materials cannot be grown on the device by deposition, or the process is extremely difficult, such as LiNbO ₃ , LiTaO ₃ and so on. It is currently common to grow an entire crystal column, then cut to a specific crystal orientation, and then attach a material of a specific available thickness to a temporary substrate.

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

SUMMARY OF THE INVENTION

The present invention is proposed to alleviate or solve at least one aspect of the above-mentioned problems in the prior art.

According to an aspect of an embodiment of the present invention, a resonator is provided, comprising: a substrate; an acoustic mirror; a resonant structure, the resonant structure includes a single-crystal piezoelectric layer and an electrode layer, the piezoelectric layer is arranged substantially parallel to the substrate; The support structure is arranged between the base and the resonance structure. The support structure defines at least a part of the boundary of the acoustic mirror in the horizontal direction, and the upper surface of the support structure is a flat surface.

The invention also relates to a method for manufacturing a resonator, the resonator comprising: a substrate; an acoustic mirror; a resonant structure, the resonant structure comprising a single crystal piezoelectric layer and an electrode layer, the piezoelectric layer and the substrate are arranged substantially parallel to the substrate; a support The structure is arranged between the substrate and the resonant structure. The method includes: forming a flat layer of support material on a flat layer; patterning the layer of support material to form a cavity for the acoustic mirror, thereby forming a support structure, the upper surface of the support structure having a first a flat surface and the lower surface has a second flat surface; and bonding the substrate and the support structure on the second flat surface.

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

Embodiments of the present invention also relate to an electronic device comprising the above-mentioned filter or the above-mentioned resonator.

Description of drawings

These and other features and advantages of the various disclosed embodiments of the present invention may be better understood by the following description and accompanying drawings, in which like reference numerals refer to like parts throughout, wherein:

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 of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention, respectively. A schematic cross-sectional view of ;

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

15-17 are schematic cross-sectional views of bulk acoustic wave resonators according to further different exemplary embodiments of the present invention, similar to line BB' in FIG. 1;

18A and 18B are a schematic plan view and a schematic cross-sectional view of a lateral vibration resonator according to an exemplary embodiment of the present invention, respectively;

Figures 19-26 are a series of diagrams illustrating the fabrication process of the lateral vibration resonator shown in Figure 18B; and

27-29 are schematic cross-sectional views of transverse vibration resonators according to further various exemplary embodiments of the present invention.

Detailed ways

The technical solutions of the present invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings. In the specification, the same or similar reference numerals refer to the same or similar parts. 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 a limitation of the present invention. Some, but not all, embodiments of the invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art fall within the protection scope of the present invention.

Embodiments of the present invention will be specifically described below with reference to FIGS. 1-29 .

The reference numerals in the drawings of the present invention are exemplified as follows:

100: Substrate, the specific material can be silicon, silicon carbide, sapphire, silicon dioxide, or other silicon-based materials.

101: Single crystal piezoelectric layer, optional single crystal aluminum nitride, single crystal gallium nitride, single crystal lithium niobate, single crystal lead zirconate titanate, single crystal potassium niobate, single crystal quartz film, or single crystal tantalum Lithium oxide and other materials can also contain rare earth element doped materials with a certain atomic ratio of the above materials, such as doped aluminum nitride, and doped aluminum nitride 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), etc.

102: Bottom electrode (electrode pin), the material can be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or a composite of the above metals or their alloys.

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

1030: Acoustic mirror, which can be a cavity, or a Bragg reflector and other equivalent forms. Cavities are used in the illustrated embodiment of the present invention.

104: Top electrode (electrode pin), the material can be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or a composite of the above metals or their alloys. The material of the top electrode can be the same or different from that of the bottom electrode.

105: Passivation layer, generally a dielectric material, such as silicon dioxide, aluminum nitride, silicon nitride, etc.

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

107: Metal pad or electrode connection part, the material can be selected from high conductivity materials such as gold, copper, and aluminum.

108: the lead-out part of the top electrode, the material is the same as that of the top electrode.

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

201: Insulation layer, material such as silicon dioxide, silicon nitride, silicon carbide, sapphire and the like.

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

As shown in FIG. 1 , FIG. 2A and FIG. 2B , the BAW resonator includes: 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 , and an electrical isolation layer 106. An electrode connecting portion 107 and a top electrode lead-out portion 108 respectively connected to the electrical connecting end of the bottom electrode and the electrical connecting end of the top electrode. In this bulk acoustic wave resonator, the top electrode, the piezoelectric layer and the bottom electrode constitute a resonance structure.

As shown in FIGS. 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 resonance structure facing the support layer 103 .

As mentioned later with reference to FIGS. 3-14 , the support layer 103 is a flat layer, the bottom electrode 102 is also a flat layer, and the support layer 103 is formed on the flat layer of the unpatterned bottom electrode 102 . In 2A, the upper surface of the support layer 103 is a flat surface (ie, the first flat surface), so that the lower surface of the support layer 103 is directly a flat surface (the second flat surface), so that the lower surface of the support layer 103 does not require additional such as CMP (chemical mechanical polishing) process to planarize the lower surface of the support layer. In this way, the lower surface of the support layer 103 only undergoes one patterning step, so its surface properties are good, which is favorable for the subsequent bonding connection between the lower surface of the support layer 103 and the substrate 100 .

It should be noted that, in the present invention, the upper surface of the support structure or the support layer (ie the surface away from the substrate 100 ) is a flat surface, which means the upper surface of the support structure or the support layer except the etched or removed part. for the plane.

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 planes that are parallel to each other.

In one embodiment of the present invention, as shown in FIG. 2A , an insulating layer 106 is provided between the electrical connection end of the top electrode 104 and the end face of the piezoelectric layer 101 , and the insulating layer 106 electrically connects the electrical connection end of the top electrode 104 Electrically isolated from bottom electrode 102 .

In an embodiment of the present invention, as shown in FIG. 2A , the resonator further includes a top electrode lead-out portion 108 arranged in the same layer as the bottom electrode 102 , and the electrode connection end of the top electrode 104 is led out from the top electrode portion 108 is electrically connected.

In one embodiment of the present invention, as shown in FIGS. 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.

Referring to FIGS. 3-14 , the fabrication process of the bulk acoustic wave resonator shown in FIG. 2A is exemplarily explained below.

As shown in FIG. 3, a POI (Piezoelectrics on Insulator, 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. As mentioned above, the single crystal piezoelectric layer can be lithium niobate, lithium tantalate, quartz, etc. Piezoelectric single crystal thin film.

The crystal orientations of piezoelectric single crystal films in POI wafers are diverse and are not limited by the growth conditions of piezoelectric films. Therefore, piezoelectric single crystal films with special crystal orientations can be selected as required to produce resonators and filters with various properties. device.

As mentioned later, during the resonator transfer process, the insulating layer 201 can better protect the single-crystal piezoelectric film (ie, the single-crystal piezoelectric layer), thereby reducing or even avoiding the subsequent removal of the auxiliary substrate. The damage to the single crystal piezoelectric film can be reduced or even avoided to the surface damage of the piezoelectric film, so as to obtain a bulk acoustic wave resonator with excellent performance.

In addition, the existence of the insulating layer 201 facilitates the separation of the piezoelectric layer 101 from the auxiliary substrate 200, facilitates the diversification of the removal scheme of the auxiliary substrate, and simplifies the device processing process.

It should be pointed out that, in an embodiment of the present invention, the POI wafer may not be used, but 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 a bottom electrode film layer for forming the bottom electrode 102 deposited or grown on the surface of the piezoelectric single crystal thin film. Obviously, the surface of the bottom electrode film layer is a straight flat surface.

FIG. 5 shows the deposition of a support material layer or a bonding material layer corresponding to the support layer 103 on the bottom electrode film layer. Obviously, since the supporting material layer is formed on the flat bottom electrode film layer, the upper surface of the supporting material layer in FIG. 5 is also a flat surface. A so-called polishing process (such as CMP) is used to planarize its surface.

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

FIG. 7 shows the bonded structure of the support layer 103 and the substrate 100 . The substrate 100 and the support layer 103 may be bonded physically or chemically, chemical bonds may be formed between the substrate 100 and the support layer 103, or physical bonds may be formed by intermolecular force. For example, the support layer 103 is silicon oxide, and the substrate 100 is silicon, so "direct bonding" can be used. At this time, the support layer 103 is grown on the non-patterned surface, and only undergoes one step of etching, so 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 only be the support layer 103, or may include the support layer 103 and another bonding material layer or other materials that will not affect the bonding connection between the resonance structure and the substrate. functional layer.

FIG. 8 shows the structure after the device shown in FIG. 7 has been inverted and the substrate 200 has been removed. FIG. 9 shows the structure after the insulating layer 201 in FIG. 8 is removed.

The etching processes of the auxiliary substrate 200 and the insulating layer 201 (barrier layer) are very different. For example, the auxiliary substrate 200 is silicon, the insulating layer 201 is silicon dioxide, and the insulating layer 201 can be terminated during the removal of the auxiliary substrate 100 Due to the function of the layer or barrier layer, the removal process of the insulating layer 201 is mild, and the damage to the other surface of the piezoelectric single crystal thin film during the process of removing the auxiliary substrate 200 is reduced or even avoided.

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

In an optional embodiment, the steps shown in FIG. 8 and FIG. 9 may also be: due to the existence of the insulating layer 201 as a barrier layer, the surface release process of the piezoelectric single crystal thin film may be formed by first forming a release on the substrate 200 hole, and then release the insulating layer material through the release hole. 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 area; For damage, a release hole can be formed in the out-of-band region of the resonator or the filter formed by the resonator (such as a scribing track), so that the device processing technology is simple.

The overall removal of the auxiliary substrate 200 or the process of forming the release holes may adopt related processes such as grinding, grinding, polishing, or a combination of these processes.

The overall removal process of the insulating layer 201 may adopt related processes such as grinding, grinding, 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 film is partially damaged, especially the effective area of the resonator or the filter formed by the resonator is damaged, the surface of the piezoelectric film can be polished through a polishing process.

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

Based on the steps shown in FIGS. 3-9 , the piezoelectric layer transfer process is realized.

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

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 . Obviously, since the piezoelectric layer 101 constitutes a barrier layer in the process of etching or patterning the bottom electrode film layer, as shown in FIG. 11 , the piezoelectric layer 101 only covers a part of the bottom electrode 102 .

As shown in FIG. 12A , an isolation material layer is formed on the structure shown in FIG. 11 , and the isolation material layer 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-electrically connected end of the bottom electrode. The isolation material layer is an electrically insulating material layer.

As shown in FIG. 12B, the isolation material layer of FIG. 12A is patterned, leaving the insulating layer 106.

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

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

As shown in FIG. 14 , electrode connecting parts or external leads 107 are provided on the structure shown in FIG. 13 , thereby forming the resonator structure shown in FIG. 2A .

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

FIG. 15 is a schematic cross-sectional view similar to the line BB in FIG. 1 of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention. As shown in FIG. 15 , the upper interface of the acoustic mirror 1030 may also be defined by the support layer 103 , that is, there is a support material layer 1031 between the acoustic mirror 1030 and the bottom electrode 102 in the thickness direction of the piezoelectric layer. Except for this, the structure of the embodiment shown in FIG. 15 is the same as that shown in FIGS. 2A-2B , and details are not repeated here.

The support material layer 1031 in FIG. 15 can have various functions. For example, when the support material is silicon oxide, it can function as a temperature compensation layer. For example, when the support material is a material with good thermal conductivity, such as diamond and silicone grease In the case of , it can help to dissipate heat and improve the power capacity of the resonator.

FIG. 16 is a schematic cross-sectional view of the bulk acoustic wave resonator according to an exemplary embodiment of the present invention, similar to the line BB in FIG. 1 . 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 connected to the supporting material layer 1031 is also provided, and the functional layer 1032 may be a material with a negative temperature coefficient such as silicon oxide, or a molybdenum , tungsten, copper and other high thermal conductivity materials, or other acoustic materials used in conjunction with the support material layer 1031 .

17 is a schematic cross-sectional view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention, similar to a line BB in FIG. 1 . The difference between the structure shown in FIG. 17 and the structure shown in FIG. 2B is that in FIG. 17 , a functional layer 1033 connected to the bottom electrode 102 and a functional layer 1032 connected to the functional layer 1033 are also provided. The material and support of the functional layer 1033 The material of layer 103 is different. The functional layer 1032 can be a material with a negative temperature coefficient such as silicon oxide, and can be a material with high thermal conductivity such as molybdenum, tungsten, and copper, and the functional layer 1033 can be a material with a negative temperature coefficient such as silicon oxide, and can be a material with high thermal conductivity such as molybdenum, tungsten, and copper. The material can also be other acoustic materials used in conjunction with the functional layer 1032 .

In the present invention, the supporting material layer 1031, the functional layer 1032 and the functional layer 1033 can also be used as acoustic reflection layers to limit the leakage of acoustic waves and improve the Q value of the FABR.

For the structure shown in FIGS. 15-17 , the fabrication process is similar to that of the structure shown in FIG. 2B , the difference is that for the structure shown in FIG. 15 , in the steps shown in FIG. 6 , the cavity formed The bottom electrode film layer is not reached. For the structure shown in FIG. 16 , relative to the structure shown in FIG. 15 , the step of forming a functional layer 1032 in the cavity is further included after the step shown in FIG. 6 . For the structure shown in FIG. 17 The structure of FIG. 6 further includes the steps of setting

functional layers

1033 and 1032 after the steps 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 repeated here.

In the embodiments shown in Figures 1-17, the resonators are bulk acoustic wave resonators, but the invention can also be applied to transverse vibration resonators.

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

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

interdigital electrodes

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

The fabrication process of the lateral vibration resonator shown in FIG. 18B is exemplarily described below with reference to FIGS. 19-26 .

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

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

FIG. 21 shows the patterning of a layer of support material by, 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, or a Bragg reflector may be provided therein to form other types of acoustic mirror structures.

FIG. 22 shows the structure after the bonding of the support layer 103 and the substrate 100, FIG. 23 shows the structure after the device shown in FIG. 22 is reversed and the substrate 200 is removed, and 24 shows the structure of the device shown in FIG. The structure in 23 after the insulating layer 201 is removed. This is similar to the above description with reference to FIGS. 7-9 and will not be repeated here.

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

FIG. 26 shows the steps of forming the

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 FIGS. 18A-26 , the upper interface of the acoustic mirror 1030 is defined by the lower surface of the bottom electrode 102, but the present invention is not limited thereto.

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 the support layer 103 , that is, there is a support material layer 1031 between the acoustic mirror 1030 and the bottom electrode 102 in the thickness direction of the piezoelectric layer. Other than that, the structure of the embodiment shown in FIG. 27 is the same as that shown in FIG. 18B , and details are not repeated here.

The support material layer 1031 in FIG. 27 can have various functions. For example, when the support material is silicon oxide, it can function as a temperature compensation layer. For example, when the support material is a material with good thermal conductivity, such as diamond and silicone grease In the case of , it can help to dissipate heat and improve the power capacity of the resonator.

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 shown in FIG. 28 and the structure shown in FIG. 27 is that in FIG. 28 , a functional layer 1032 connected to the supporting material layer 1031 is also provided. The functional layer 1032 may be a material with a negative temperature coefficient such as silicon oxide, or a molybdenum , tungsten, copper and other high thermal conductivity materials, or other acoustic materials used in conjunction with the support material layer 1031 .

29 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 shown in FIG. 29 and the structure shown in FIG. 18B is that in FIG. 29 , a functional layer 1033 connected to the bottom electrode 102 and a functional layer 1032 connected to the functional layer 1033 are also provided. The material and support of the functional layer 1033 The material of layer 103 is different. The functional layer 1032 can be a material with a negative temperature coefficient such as silicon oxide, and can be a material with high thermal conductivity such as molybdenum, tungsten, and copper, and the functional layer 1033 can be a material with a negative temperature coefficient such as silicon oxide, and can be a material with high thermal conductivity such as molybdenum, tungsten, and copper. The material can also be other acoustic materials used in conjunction with the functional layer 1032 .

In the present invention, the supporting material layer 1031, the functional layer 1032 and the functional layer 1033 can also be used as acoustic reflection layers to limit the leakage of acoustic waves and improve the Q value of XABR.

For the structure shown in Figures 27-29, the fabrication process is similar to that of the structure shown in Figure 18B, except that for the structure shown in Figure 27, in the steps shown in Figure 21, the cavity formed The bottom electrode film layer is not reached. For the structure shown in FIG. 28 , compared with the structure shown in FIG. 27 , the step of forming a functional layer 1032 in the cavity is further included after the step shown in FIG. 21 . For the structure shown in FIG. 29 The structure of FIG. 21 further includes the steps of setting

functional layers

1033 and 1032 after the steps shown in FIG. 21 . Other steps are the same as or similar to the manufacturing process of the structure shown in FIG. 18B , and will not be repeated here.

In the present invention, upper and lower are relative to the bottom surface of the base of the resonator. For a component, the side close to the bottom surface is the lower side, and the side away from the bottom surface is the upper side.

In the present invention, inside and outside are relative to the center of the effective area 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) (ie, the center of the effective area). ) in the transverse or radial direction, the side or end of a component close to the center of the effective area is the inner or inner end, and the side or end of the component away from the center of the effective area is the outer or outer end. For a reference position, being located inside the position means being between the position and the center of the active area in the lateral or radial direction, and being located outside of the position means being farther from the position in the lateral or radial direction than the position Effective regional center.

As can be appreciated by those skilled in the art, BAW resonators according to the present invention may be used to form filters or electronic devices.

Based on the above, the present invention proposes the following technical solutions:

1. A resonator comprising:

base;

acoustic mirror;

a resonance structure, the resonance structure includes a single crystal piezoelectric layer and an electrode layer, and the piezoelectric layer is arranged substantially parallel to the substrate;

a support structure arranged between the base and the resonant structure,

in:

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

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 includes a top electrode and a bottom electrode respectively arranged on both sides of the piezoelectric layer;

The bottom electrode is disposed on the upper surface of the support structure, the bottom electrode is a flat electrode, and the lower surface of the bottom electrode defines the surface of the resonance structure facing the flat surface.

3. The resonator of claim 2, wherein:

An insulating layer is disposed between the electrical connection end of the top electrode and the end face of the piezoelectric layer, and the insulating layer electrically isolates the electrical connection end of the top electrode from the bottom electrode.

4. The resonator of claim 3, wherein:

The resonator further includes a top electrode lead-out portion arranged in the same layer as the bottom electrode, and an electrode connection end of the top electrode is electrically connected to the top electrode lead-out portion.

5. The resonator of claim 2, wherein:

the bottom electrode defines at least a portion of the 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 lateral vibration resonator, and the electrode layer includes interdigital electrodes arranged on the upper surface of the piezoelectric layer;

The lower surface of the piezoelectric layer defines the surface of the resonant structure that faces the flat surface.

7. The resonator of claim 1, wherein:

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

8. The resonator of claim 7, wherein:

The at least one functional layer includes at least one of a temperature compensation layer, a thermally conductive material layer, and an acoustic material layer.

9. The resonator of claim 1, wherein:

Portions of the lower surface of the resonance structure and the upper surface of the support structure facing each other are in 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 for manufacturing a resonator, the resonator comprising a substrate; an acoustic mirror; a resonant structure, the resonant structure comprising a single crystal piezoelectric layer and an electrode layer, the piezoelectric layer and the substrate are arranged substantially parallel to the substrate; a support structure, set Between the substrate and the resonant structure, the method includes:

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

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

The substrate is bonded to the support structure at the second flat surface.

12. The method of claim 11, wherein:

The resonator is a bulk acoustic wave resonator, the electrode layer includes a top electrode and a bottom electrode respectively arranged on both sides of the piezoelectric layer, and the method includes:

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

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

Step 3: forming a straight support material layer on the bottom electrode material layer, the upper surface of the support material layer has a first flat surface and the lower surface has a second flat surface, the bottom electrode material layer constitutes the straight layer;

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

Step 5: bonding the substrate with the support structure on the second flat surface;

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

Step 7: Pattern the piezoelectric layer;

Step 8: patterning the bottom electrode material layer to form the bottom electrode;

Step 9: Disposing the top electrode on the first side of the piezoelectric layer.

13. The method of claim 12, wherein:

Step 1 includes: providing a POI wafer, the POI wafer including a substrate, a single crystal piezoelectric layer, and an insulating layer disposed between the first side of the single crystal piezoelectric layer and the substrate;

Step 2 includes: forming a flat bottom electrode material layer on a second side opposite to the first side of the piezoelectric layer of the POI wafer;

Step 6 includes: removing the substrate and some or all of the insulating layer, at least a portion of the insulating layer is removed to expose the first side of the piezoelectric layer, and the first side of the piezoelectric layer is effective with the resonator The insulating layer corresponding to the area is removed.

14. The method of claim 12, wherein:

Between step 8 and step 9, step 10 is further included: providing an insulating layer, the insulating layer covering at least the end face of the piezoelectric layer and the end face of the non-electrically connected end of the bottom electrode;

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

15. The method of claim 14, wherein:

In step 8, the bottom electrode material layer is patterned to form a bottom electrode and a top electrode lead-out portion at the same time;

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 lateral vibration resonator, the electrode layer includes interdigital electrodes disposed on the upper surface of the piezoelectric layer, and the method includes:

Step 2: forming a flat supporting material layer on a second side of the piezoelectric layer opposite to the first side, the supporting material layer having a flat surface, and the piezoelectric layer constituting the flat layer;

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

Step 4: bonding the substrate with the support structure on the second flat surface;

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

Step 6: Disposing the interdigital electrodes on the first side of the piezoelectric layer.

17. The method of claim 16, wherein:

Step 5 includes removing the substrate and some or all of the insulating layer, at least a portion of the insulating layer being removed to expose the first side of the piezoelectric layer.

18. The method of claim 16, further comprising:

Step 7: Pattern the piezoelectric layer.

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 equipment here includes but is not limited to intermediate products such as RF front-end, filter and amplifier modules, and terminal products such as mobile phones, WIFI, and drones.

Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that changes may be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is determined by It is defined by the appended claims and their equivalents.

Claims

A resonator comprising:

base;

acoustic mirror;

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

a support structure arranged between the base and the resonant structure,

in:

a support structure defining at least a portion of a horizontal boundary of the acoustic mirror; and

The upper surface of the support structure is a flat surface.
The resonator of claim 1, wherein:

The resonator is a bulk acoustic wave resonator, and the electrode layer includes a top electrode and a bottom electrode respectively disposed on both sides of the piezoelectric layer; and

The bottom electrode is disposed on the upper surface of the support structure, the bottom electrode is a flat electrode, and the lower surface of the bottom electrode defines the surface of the resonance structure facing the flat surface.
The resonator of claim 2, wherein an insulating layer is provided between the electrical connection end of the top electrode and the end face of the piezoelectric layer, and the insulating layer electrically isolates the electrical connection end of the top electrode from the bottom electrode.
The resonator according to claim 3, wherein the resonator further comprises a top electrode lead-out portion arranged in the same layer as the bottom electrode, and an electrode connection end of the top electrode is electrically connected to the top electrode lead-out portion.
The resonator of claim 2, wherein:

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

The support structure defines at least a portion of an upper surface of the acoustic mirror.
The resonator of claim 1, wherein:

The resonator is a lateral vibration resonator, and the electrode layer includes interdigitated electrodes disposed on the upper surface of the piezoelectric layer; and

The lower surface of the piezoelectric layer defines the surface of the resonant structure that faces the flat surface.
The resonator according to 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 the material of the support structure.
The resonator of claim 7, wherein the at least one functional layer comprises at least one of a temperature compensation layer, a thermally conductive material layer, and an acoustic material layer.
The resonator of claim 1, wherein the lower surface of the resonance structure and the upper surface of the support structure are in surface contact with portions facing each other.
The resonator according to any one of claims 1-9, wherein the piezoelectric layer is a lithium niobate piezoelectric layer or a lithium tantalate piezoelectric layer.
A method for manufacturing a resonator, the resonator includes a substrate; an acoustic mirror; a resonant structure, the resonant structure includes a single-crystal piezoelectric layer and an electrode layer, the piezoelectric layer is arranged substantially parallel to the substrate; a support structure is arranged on the substrate and the resonant structure, the method includes:

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

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

The substrate is bonded to the support structure at the second flat surface.
The method of claim 11, wherein:

The resonator is a bulk acoustic wave resonator, the electrode layer includes a top electrode and a bottom electrode respectively arranged on both sides of the piezoelectric layer, and the method includes:

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

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

Step 3: forming a straight support material layer on the bottom electrode material layer, the upper surface of the support material layer has a first flat surface and the lower surface has a second flat surface, the bottom electrode material layer constitutes the straight layer;

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

Step 5: bonding the substrate with the support structure on the second flat surface;

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

Step 7: Pattern the piezoelectric layer;

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

Step 9: Disposing the top electrode on the first side of the piezoelectric layer.
The method of claim 12, wherein:

Step 1 includes: providing a POI wafer, the POI wafer including a substrate, a single crystal piezoelectric layer, and an insulating layer disposed between the first side of the single crystal piezoelectric layer and the substrate;

Step 2 includes: forming a flat bottom electrode material layer on a second side of the piezoelectric layer of the POI wafer opposite the first side; and

Step 6 includes: removing the substrate and some or all of the insulating layer, at least a portion of the insulating layer is removed to expose the first side of the piezoelectric layer, and the first side of the piezoelectric layer is effective with the resonator The insulating layer corresponding to the area is removed.
The method of claim 12, wherein:

Between step 8 and step 9, step 10 is further included: providing an insulating layer, the insulating layer covering at least the end face of the piezoelectric layer and the end face of the non-electrically connected end of the bottom electrode; and

In step 9, the electrical connection end of the top electrode covers at least a part of the insulating layer.
The method of claim 14, wherein:

In step 8, patterning the bottom electrode material layer to simultaneously form the bottom electrode and the top electrode lead-out portion; and

In step 9, the electrode connection end of the top electrode is electrically connected to the top electrode lead-out portion.
The method of claim 11, wherein:

The resonator is a lateral vibration resonator, the electrode layer includes interdigital electrodes disposed on the upper surface of the piezoelectric layer, and the method includes:

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

Step 2: forming a flat supporting material layer on a second side of the piezoelectric layer opposite to the first side, the supporting material layer having a flat surface, and the piezoelectric layer constituting the flat layer;

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

Step 4: bonding the substrate with the support structure on the second flat surface;

Step 5: removing the substrate, exposing the first side of the piezoelectric layer; and

Step 6: Disposing the interdigital electrodes on the first side of the piezoelectric layer.
The method of claim 16, wherein:

Step 1 includes: providing a POI wafer including 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; and

Step 5 includes removing the substrate and some or all of the insulating layer, at least a portion of the insulating layer being removed to expose the first side of the piezoelectric layer.
The method of claim 16, further comprising:

Step 7: Pattern the piezoelectric layer.
A filter comprising a resonator according to any of claims 1-10.
An electronic device comprising a filter according to claim 19, or a resonator according to any one of claims 1-10.