阅读说明：本技术 声学谐振器封装结构 (Acoustic resonator packaging structure ) 是由 李亮 商庆杰 梁东升 赵洋 王利芹 丁现朋 刘青林 冯利东 张丹青 崔玉兴 张力 于 2019-10-11 设计创作，主要内容包括：本发明涉及半导体技术领域,具体公开一种声学谐振器封装结构。该谐振器包括基板；声学谐振器,设置在所述基板上,所述声学谐振器包括衬底；多层结构,形成于所述衬底上,其中,在所述衬底和所述多层结构之间形成有腔体；盖帽,所述盖帽与所述基板之间形成一个密封空间；材料层区域；以及电子电路,形成于所述材料层区域上,从而形成一种新型的声学谐振器封装结构,且具有较好的性能。(The invention relates to the technical field of semiconductors, and particularly discloses an acoustic resonator packaging structure. The resonator includes a substrate; an acoustic resonator disposed on the substrate, the acoustic resonator comprising a substrate; a multilayer structure formed on the substrate, wherein a cavity is formed between the substrate and the multilayer structure; the cap forms a sealed space with the substrate; a material layer region; and the electronic circuit is formed on the material layer area, so that a novel acoustic resonator packaging structure is formed, and the acoustic resonator packaging structure has better performance.)

1. An acoustic resonator package structure, comprising:

a substrate provided with a peripheral pad;

an acoustic resonator disposed on the substrate, the acoustic resonator including a substrate and a multilayer structure; the multilayer structure is formed on the substrate and sequentially comprises a lower electrode layer, a piezoelectric layer and an upper electrode layer from bottom to top; a cavity is formed between the substrate and the multilayer structure, and comprises a lower half cavity below the upper surface of the substrate and an upper half cavity which exceeds the upper surface of the substrate and protrudes towards the multilayer structure;

the cap is provided with a peripheral bonding pad sealing element, and the peripheral bonding pad sealing element is connected with the peripheral bonding pad so that a sealing space is formed between the cap and the substrate;

a layer region of material disposed on a first cap surface of the cap within the sealed space; and

an electronic circuit formed on the material layer area.

2. The acoustic resonator package of claim 1, wherein: the lower half cavity is enclosed by a bottom wall and a first side wall, the whole bottom wall is parallel to the surface of the substrate, and the first side wall is a first smooth curved surface extending from the edge of the bottom wall to the upper surface of the substrate.

3. The acoustic resonator package of claim 2, wherein: the first smooth curved surface comprises a first curved surface and a second curved surface which are in smooth transition connection, and the vertical section of the first curved surface is in an inverted parabolic shape and is positioned on the plane of the bottom wall; the vertical section of the second curved surface is parabolic and is positioned below the plane of the upper surface of the substrate.

4. The acoustic resonator package of claim 1, wherein: the upper half cavity is formed by surrounding the lower side surface of the multilayer structure, the part of the multilayer structure corresponding to the upper half cavity comprises a top wall and a second side wall, and the second side wall is a second smooth curved surface which is formed by extending the edge of the top wall to the upper surface of the substrate.

5. The acoustic resonator package of claim 4, wherein: the second smooth curved surface comprises a third curved surface and a fourth curved surface which are in smooth transition connection, and the vertical section of the third curved surface is in a parabolic shape and is positioned below the plane of the top wall; the vertical section of the fourth curved surface is in an inverted parabolic shape and is positioned on the plane of the upper surface of the substrate.

6. The acoustic resonator package of claim 1, wherein: the electronic circuit is electrically connected to the acoustic resonator.

7. The acoustic resonator package of claim 1, wherein: the substrate is further provided with a first bonding pad, and the peripheral bonding pad surrounds the first bonding pad.

8. The acoustic resonator package of claim 7, wherein: the cap is further provided with a pad seal, and the pad seal is bonded to the periphery of the first pad.

9. The acoustic resonator package of claim 7, wherein: a through hole is provided in the cap, the through hole being located above the first pad to provide a path for electrical connection to the first pad.

10. The acoustic resonator package of claim 7, wherein: a through hole is formed in the substrate, is located below the first bonding pad, and provides a path for electrical connection to the first bonding pad.

11. The acoustic resonator package of claim 7, wherein: the material layer region is electrically isolated from the pad seal.

12. The acoustic resonator package of claim 7, wherein: the substrate is provided with a second bonding pad, and the cover cap is provided with a pull-down contact column connected with the second bonding pad.

13. The acoustic resonator package of claim 1, wherein: the material layer region is composed of a material having a lower resistivity than the cap.

14. The acoustic resonator package of claim 1, wherein: the substrate includes a first substrate surface disposed opposite the first surface of the cap, the first substrate surface including at least one recessed region disposed opposite the acoustic resonator.

15. The acoustic resonator package of any of claims 1-14, wherein: the electronic circuit is directly opposite the acoustic resonator.

16. The acoustic resonator package of claim 1, wherein: the cap is a semiconductor cap, and the material layer region is an epitaxial layer region formed on the cap substrate.

17. The acoustic resonator package of claim 1, wherein: the electronic circuit is coupled with the acoustic resonator to form an ultra-low phase noise oscillator.

Technical Field

The invention relates to the technical field of semiconductors, in particular to an acoustic resonator packaging structure.

Background

Resonators may be used in various electronic applications to implement signal processing functions, for example, some cellular telephones and other communication devices use resonators to implement filters for transmitted and/or received signals. Several different types of resonators may be used depending on different applications, such as Film Bulk Acoustic Resonators (FBARs), coupled resonator filters (SBARs), Stacked Bulk Acoustic Resonators (SBARs), Dual Bulk Acoustic Resonators (DBARs), and solid State Mounted Resonators (SMRs).

A typical acoustic resonator includes an upper electrode, a lower electrode, a piezoelectric material between the upper and lower electrodes, an acoustically reflective structure under the lower electrode, and a substrate under the acoustically reflective structure. The area where the three materials of the upper electrode, the piezoelectric layer and the lower electrode are overlapped in the thickness direction is generally defined as the effective area of the resonator. When a voltage signal with a certain frequency is applied between the electrodes, due to the inverse piezoelectric effect of the piezoelectric material, a sound wave which is vertically transmitted can be generated between the upper electrode and the lower electrode in the effective area, and the sound wave is reflected back and forth between the interface of the upper electrode and the air and the sound reflection structure below the lower electrode and generates resonance under a certain frequency.

At present, the traditional resonator manufacturing method is not easy to control the surface roughness of the resonator working area, and influences the resonator performance. Furthermore, in past acoustic resonator package structures, the electrical signals transmitted by the leads or wires between the packaged acoustic element and external electronic circuitry are susceptible to loss, noise and/or interference due to the interconnection length of the leads, thereby degrading the performance of the device. Accordingly, improvements and optimizations for resonators and resonator packaging structures are needed.

Disclosure of Invention

The invention provides an acoustic resonator packaging structure, aiming at the problems that the surface roughness of a resonator working area is not easy to control, the performance of a resonator is influenced and the electric signal stability of the resonator packaging structure is influenced in the existing resonator manufacturing method.

In order to achieve the purpose of the invention, the embodiment of the invention adopts the following technical scheme:

an acoustic resonator package structure comprising:

a substrate provided with a peripheral pad;

an acoustic resonator disposed on the substrate, the acoustic resonator including a substrate and a multilayer structure; the multilayer structure is formed on the substrate and sequentially comprises a lower electrode layer, a piezoelectric layer and an upper electrode layer from bottom to top; a cavity is formed between the substrate and the multilayer structure, and comprises a lower half cavity below the upper surface of the substrate and an upper half cavity which exceeds the upper surface of the substrate and protrudes towards the multilayer structure;

the cap is provided with a peripheral bonding pad sealing element, and the peripheral bonding pad sealing element is connected with the peripheral bonding pad so that a sealing space is formed between the cap and the substrate;

a layer region of material disposed on a first cap surface of the cap within the sealed space; and

an electronic circuit formed on the material layer area.

Optionally, the lower half cavity is enclosed by a bottom wall and a first side wall, the bottom wall is entirely parallel to the substrate surface, and the first side wall is a first smooth curved surface extending from an edge of the bottom wall to the upper surface of the substrate.

Optionally, the first smooth curved surface includes a first curved surface and a second curved surface which are connected in a smooth transition manner, and a vertical cross section of the first curved surface is in an inverted parabolic shape and is located on a plane where the bottom wall is located; the vertical section of the second curved surface is parabolic and is positioned below the plane of the upper surface of the substrate.

Optionally, the upper half cavity is defined by a lower side surface of the multilayer structure, a portion of the multilayer structure corresponding to the upper half cavity is defined by a top wall and a second side wall, and the second side wall is a second smooth curved surface extending from an edge of the top wall to an upper surface of the substrate.

Optionally, the second smooth curved surface includes a third curved surface and a fourth curved surface that are connected in a smooth transition manner, and a vertical cross section of the third curved surface is parabolic and is located below a plane where the top wall is located; the vertical section of the fourth curved surface is in an inverted parabolic shape and is positioned on the plane of the upper surface of the substrate.

Optionally, the electronic circuit is electrically connected to the acoustic resonator.

Optionally, the substrate is further provided with a first pad, and the peripheral pad surrounds the first pad.

Optionally, the cap is further provided with a pad seal, and the pad seal is bonded to the periphery of the first pad.

Optionally, a through hole is provided in the cap, the through hole being located above the first pad to provide a path for an electrical connection to the first pad.

Optionally, a through hole is provided on the substrate, the through hole being located below the first pad to provide a path for electrical connection to the first pad.

Optionally, a second pad is disposed on the substrate, and a pull-down contact column connected to the second pad is disposed on the cap.

Optionally, the material layer region is electrically isolated from the pad seal.

Optionally, the material layer region is composed of a material having a lower resistivity than the cap.

Optionally, the substrate includes a first substrate surface disposed opposite the first surface of the cap, the first substrate surface including at least one recessed region disposed opposite the acoustic resonator.

Optionally, the electronic circuit is directly opposite the acoustic resonator.

Optionally, the cap is a semiconductor cap, and the material layer region is an epitaxial layer region formed on the cap substrate.

Optionally, the electronic circuit is coupled with the acoustic resonator to form an ultra low phase noise oscillator.

Compared with the prior art, the beneficial effects produced by adopting the technical scheme are as follows: according to the embodiment of the invention, the cavity with the lower half cavity and the upper half cavity is arranged, the lower half cavity is integrally positioned below the upper surface of the substrate, and the upper half cavity is integrally positioned above the upper surface of the substrate, so that a novel resonator structure is formed and has better performance, and the resonator and the electronic circuit are jointly used for a resonator packaging structure, so that the resonator packaging structure with stable performance is obtained.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a schematic structural diagram of an acoustic resonator package structure according to an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of an acoustic resonator package structure according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of the structure of an acoustic resonator in an embodiment of the present invention;

FIG. 4 is an enlarged schematic view of A in FIG. 3;

FIG. 5 is a flow chart of a method of making an acoustic resonator in an embodiment of the present invention;

fig. 6 is a flow chart of yet another method of making an acoustic resonator in an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

Referring to fig. 1 and 3, an embodiment of the invention provides an acoustic resonator package structure 100 including a substrate 110 and a cap 120. The substrate 110 has a first substrate surface (i.e., an upper surface in the drawing) provided with first pads 111, second pads 113, and a recessed region 114. The substrate 110 further includes peripheral pads (not shown) disposed on the first substrate surface. In addition, additional pads (111 and 113) are included in some embodiments of the package structure 100.

The cap 120 includes a pad seal 121, a via 122 corresponding to the pad 121, a pull-down contact post 123, a low resistivity material layer (e.g., epitaxial layer) region 125, and an electronic circuit 126 formed on the low resistivity material layer region 125 on a first cap surface (lower surface in the figure). The pad seal 121 is disposed on the support 151, and a conductive layer is disposed outside the pad seal 121 and the support 151, the pull-down contact stud 123 is disposed on the support 153, and a conductive layer is disposed outside the pull-down contact stud 123 and the support 153. The cap 120 also includes a peripheral pad seal (not shown) disposed on the first cap surface. In addition, in some embodiments, the cap 120 further includes additional pad seals 121 and corresponding vias 122, and/or additional pull-down contact posts 123. In some embodiments, one or more vias 122 on cap 120 are plated or filled with a conductive material (e.g., metal) to provide electrical connection for the corresponding metal layer of pad seal 121 and the second cap surface (top surface in the figure) of cap 520.

The acoustic resonator package 100 described above further includes an acoustic resonator 115 disposed on the recessed region 114 of the substrate 110. In some embodiments, the acoustic resonator 115 is electrically connected to the electronic circuit 126, for example, through the second bonding pad 113 and a conductive layer (e.g., metal) on the pull-down contact post 123. In some embodiments, the acoustic resonator 115 includes a Film Bulk Acoustic Resonator (FBAR), in other embodiments a rigidly mounted resonator (SMR) may be used.

In some embodiments, the base plate 110 and/or the cap 120 are comprised of a semiconductor substrate. And in some embodiments cap 120 may be made of an electronically non-conductive material or a high resistivity semiconductor material (e.g., single crystal silicon). In alternative embodiments, the cap 120 may be comprised of other high resistivity material, such as a silicon-on-insulator (SOI) substrate, and the low resistivity material layer region 125 is formed by controlled doping of the SOI substrate.

In some embodiments, the substrate 110 and the cap 120 are made of materials having the same or approximately the same Coefficient of Thermal Expansion (CTE) as each other to avoid thermal expansion mismatch issues. In some embodiments, the substrate 110 and the cap 120 are made of the same semiconductor material as each other.

The standoffs 151 and 153, which are provided on the first cap surface of the cap 120, are formed of a material different from the semiconductor material of the cap 120. And in some embodiments, supports 151 and 153 are constructed of an electrically insulating material that may be covered with one or more electrically conductive layers (e.g., metal layers). In other embodiments, the standoffs 151 and 153 may also be constructed of a solid conductive material, such as copper or gold. By using the standoffs 151 and 153, the distance between the first cap surface of the cap 120 and the substrate 110 may be increased. Such that the electronic circuit 126 may be positioned directly above and below the resonator 115 in the package structure 100. Therefore, package structure 100 may have a shorter length or lateral dimension, all other factors being equal.

In some embodiments of the present invention, one or more portions of the low resistivity material layer between the pad seal 121, the pull-down contact post 123, and the peripheral pad seal are removed, thereby eliminating a current path through the low resistivity material layer between any of the pad seal 121, the pull-down contact post 123, and the peripheral pad seal. Further, in some embodiments, one or more portions of the low resistivity material layer are removed, thereby eliminating a current path between the low resistivity material layer region 125 and some or all of the pad seal 121, the pull-down contact post 123, and the conductive layer of the peripheral pad seal.

As an implementable manner of the embodiments of the present invention, referring to fig. 5, the low resistivity material layer (e.g., epitaxial layer) of package structure 100 is eliminated except for the following: (1) a region 125 of low resistivity material layer (e.g., epitaxial layer) isolated from part or all of the pad seal 121 and/or the pull-down contact stud 123 and/or the peripheral pad seal; (2) regions of low resistivity material layer (e.g., epitaxial layer) are located on the treads of one or more of the pad seal 121, the pull-down contact posts 123, and the peripheral pad seal. In addition, the cap 120 includes an electrically insulating material 527 (e.g., oxide silicon oxide) to electrically isolate the current path between the region 125 of low resistivity material layer (e.g., epitaxial layer) and one or more conductive layers or pad seals 121 and the pull-down contact posts 123. In certain embodiments, electrically insulating material 127 partially or completely contains or surrounds region 125 of low resistivity material layer (e.g., epitaxial layer).

As an implementable manner of the embodiment of the present invention, the support 151 of the package structure 100 is composed of a solid conductive material, such as copper or gold, and the through-hole 122 does not penetrate through the support 151 to reach the first pad 111. In this case, the seat 151 may be considered as a gasket on the first cap surface of the cap 120.

Referring to fig. 2, an acoustic resonator package 200, which is an implementable manner of an embodiment of the present invention, includes a substrate 210 and a cap 220. A first substrate surface (i.e., an upper surface in the drawing) of the substrate 210 is provided with first pads 211, through-holes 212 corresponding to the first pads 211 and formed on the substrate 210, second pads 213, and a recess region 214. The substrate 610 also includes peripheral pads (not shown) disposed on the first substrate surface. In addition, additional first pads 211 and corresponding vias 212, and additional second pad pads 213 are also included in some embodiments of package structure 200.

A first cap surface (the lower surface in the figure) of cap 220 is provided with a pull-down contact column 223, a region 225 of low resistivity material layer (e.g., epitaxial layer), and an electronic circuit 226 formed on the region 225 of low resistivity material layer. The pull-down contact stud 223 is disposed on the support 253, and one or more conductive layers are disposed outside the pull-down contact stud 223 and the support 253. The cap 220 also includes a peripheral pad seal (not shown) disposed on the first cap surface. Further, in some embodiments, the cap 220 also includes additional pull-down contact posts 223.

In some embodiments, one or more vias 212 on substrate 210 are plated or filled with a conductive material (e.g., metal) to provide electrical connection for corresponding first pads 211 and the second substrate surface (lower surface in fig. 2) of substrate 210.

The acoustic resonator package 200 described above further includes an acoustic resonator 215 disposed on the recessed region 214 of the substrate 210. In some embodiments, the acoustic resonator 215 is electrically connected to the electronic circuitry 226, for example by a pull-down contact post 223. In some embodiments, acoustic resonator 215 comprises a Film Bulk Acoustic Resonator (FBAR), in other embodiments a rigidly mounted resonator (SMR) may be used.

In some embodiments, the base 210 and/or the cap 220 are comprised of a semiconductor substrate. And in some embodiments cap 220 may be made of an electronically non-conductive material or a high resistivity semiconductor material (e.g., single crystal silicon). In some embodiments, the substrate 610 and the cap 620 are made of materials having the same or approximately the same Coefficient of Thermal Expansion (CTE) as each other to avoid thermal expansion mismatch issues. In some embodiments, the substrate 210 and the cap 220 are made of the same semiconductor material as each other.

As an enabling mode of an embodiment of the present invention, the layer of low resistivity material 225 located in the cap 220 of the package structure 200 is electrically isolated from some or all of the pull-down contact posts 223 and/or the conductive layer (e.g., metal layer) of the peripheral pad seal.

The support 253 provided on the first cap surface of the cap 220 is formed of a material different from the semiconductor material of the cap 220. And in some embodiments, standoffs 253 are comprised of an electrically insulating material that may be covered with one or more electrically conductive layers (e.g., metal layers). By using the standoff 253, the distance between the first cap surface of the cap 220 and the substrate 210 may be increased. So that the electronic circuit 226 may be directly disposed opposite the resonator 215 above and below in the package structure 200. Therefore, package structure 200 may have a shorter length or lateral dimension, all other factors being equal.

As an implementable manner of the embodiment of the present invention, in the package structure 200, compared to the package structure 100 described above, the through hole 212 is provided in the substrate 210 instead of the cap 220, so that the epitaxial layer at the first cap surface of the cap 220 can be kept intact and electrically isolated by the support 253.

As an implementable manner of the embodiment of the present invention, referring to fig. 3, in the acoustic resonator, the lower half cavity 5310 is surrounded by a bottom wall 5101 and a first side wall 5102, the bottom wall 5101 is entirely parallel to the surface of the substrate 5100, and the first side wall 5102 is a first smoothly curved surface extending from the edge of the bottom wall 5101 to the upper surface of the substrate 5100.

Wherein the bottom wall 5101 and the first side wall 5102 are both surface walls of the substrate 5100. The first side wall 5102 is a first smooth curved surface, so that the performance of the resonator cavity can be guaranteed, and sudden change is avoided.

As an implementation manner of the embodiment of the present invention, referring to fig. 3 and 4, the first smoothly curved surface may include a first curved surface 1021 and a second curved surface 1022 which are smoothly transited. The first curved surface 1021 and the second curved surface 1022 in smooth transition connection mean that the joint between the first curved surface 1021 and the second curved surface 1022 is free of sudden change, and the first curved surface 1021 and the second curved surface 1022 are also free of sudden change, so that the performance of the resonator cavity can be ensured. Where the substrate 5100 is composed of many crystals (e.g., silicon crystals), the absence of abrupt changes means that the gap between the individual crystals at the first rounded curved surface should not be too large to affect the performance of the resonator.

For example, the vertical cross-section of the first curved surface 1021 may be an inverted parabola above the plane of the bottom wall 5101, i.e., the vertex of the parabola is tangent to the plane; the vertical cross-section of the second curved surface 1022 may be parabolic and located below the plane of the upper surface of the substrate 5100, i.e., the vertex of the parabola is tangent to the plane. The first curved surface 1021 and the second curved surface 1022 are smoothly connected. Of course, the first curved surface 1021 and the second curved surface 1022 may be curved surfaces having other shapes, and the gap between the crystals at the first smooth curved surface may not affect the performance of the resonator.

As an implementable manner of the embodiment of the present invention, referring to fig. 3, the upper half cavity 5320 may be surrounded by the lower side surface of the multi-layer structure 5200, a portion of the lower side surface of the multi-layer structure 5200 corresponding to the upper half cavity 5320 includes a top wall 5201 and a second side wall 5202, and the second side wall 5202 is a second smooth curved surface extending from an edge of the top wall 5201 to the upper surface of the substrate 5100.

The top wall 5201 and the second side wall 5202 are both lower side walls of the multi-layer structure 5200. The second side wall 5202 is a second smooth curved surface, which can ensure the performance of the resonator cavity without sudden change.

As an implementation manner of the embodiment of the present invention, referring to fig. 3 and 4, the second smoothly curved surface may include a third curved surface 2021 and a fourth curved surface 2022 which are smoothly transited. The third curved surface 2021 and the fourth curved surface 2022 which are connected in a smooth transition manner mean that the joint between the third curved surface 2021 and the fourth curved surface 2022 has no abrupt change, and the third curved surface 2021 and the fourth curved surface 2022 are also curved surfaces without abrupt changes, so that the performance of the resonator cavity can be ensured. Where the substrate 5100 is composed of many crystals (e.g., silicon crystals) from a crystal perspective, no abrupt change means that the gap between the crystals at the second rounded curved surface should not be too large to affect the performance of the resonator.

For example, the vertical cross section of the third curved surface 2021 may be parabolic and located below the plane of the top wall 5201, i.e., the vertex of the parabola is tangent to the plane; the vertical section of the fourth curved surface 2022 is in an inverted parabolic shape and is located above the plane of the upper surface of the substrate 5100, i.e., the vertex of the parabola is tangent to the plane. Of course, the third curved surface 2021 and the fourth curved surface 2022 may have other shapes, and the gap between the crystals at the first rounded curved surface may not affect the performance of the resonator.

Further, referring to fig. 3, the top wall 5201 also has no abrupt portion. The abrupt changes described here are consistent with the previously described abrupt changes, and from a crystal standpoint, the multilayer structure 5200 is also comprised of many crystals, with no abrupt changes meaning that the gaps between the individual crystals at the top wall 5201 should not be too large to affect the performance of the resonator.

In the above embodiments, the substrate 5100 may be a silicon substrate or a substrate made of other materials, which is not limited thereto.

In the resonator, the cavity 5300 with the lower half cavity 5310 and the upper half cavity 5320 is arranged, the lower half cavity 5310 is integrally positioned below the upper surface of the substrate 5100, and the upper half cavity 5320 is integrally positioned above the upper surface of the substrate 5100, so that a novel resonator structure is formed and the resonator has better performance.

Referring to fig. 5, an embodiment of the present invention discloses a method for manufacturing a resonator, including the following steps:

step 301, preprocessing the substrate, and changing a preset reaction rate of a preset region part of the substrate, so that the preset reaction rate corresponding to the preset region part is greater than a preset reaction rate corresponding to a non-preset region part.

In this step, the preset reaction rate of the preset region portion of the substrate is made to reach an effect that the preset reaction rate corresponding to the preset region portion is greater than the preset reaction rate corresponding to the non-preset region portion by preprocessing the preset region portion of the substrate, so that the reaction rate of the preset region portion and the reaction rate of the non-preset region portion are different when the preset reaction is performed on the substrate in the subsequent step 302, so as to generate the sacrificial material portion in the preset shape.

Step 302, performing the preset reaction on the substrate to generate a sacrificial material part; the sacrificial material portion includes an upper half located above the upper surface of the substrate and a lower half located below the lower surface of the substrate.

Wherein the lower half part is enclosed by a bottom surface and a first side surface; the bottom surface is entirely parallel to the surface of the substrate, and the first side surface is a first smooth curved surface extending from the edge of the bottom wall to the upper surface of the substrate. The upper half part is surrounded by the lower side surface of the multilayer structure, the part of the multilayer structure corresponding to the upper half part comprises a top surface and a second side surface, and the second side surface is a second smooth curved surface extending from the edge of the top surface to the upper surface of the substrate.

Optionally, the first smooth curved surface includes a first curved surface and a second curved surface which are in smooth transition connection; the vertical section of the first curved surface is in an inverted parabolic shape and is positioned on the plane of the bottom surface; the vertical section of the second curved surface is parabolic and is positioned below the plane of the upper surface of the substrate.

Optionally, the second smooth curved surface includes a third curved surface and a fourth curved surface which are in smooth transition connection; the vertical section of the third curved surface is parabolic and is positioned below the plane of the top surface; the vertical section of the fourth curved surface is in an inverted parabolic shape and is positioned on the plane of the upper surface of the substrate.

As an implementable aspect of the embodiment of the present invention, a curvature of the first smooth curved surface is smaller than a first preset value; and the curvature of the second smooth curved surface is smaller than a second preset value.

It can be understood that, since the preset reaction rate corresponding to the preset region part is greater than the preset reaction rate corresponding to the non-preset region part, when the preset reaction is performed on the substrate, the reaction of the preset region part is fast and the reaction of the non-preset region part is slow, so that the sacrificial material part with the preset shape can be generated.

As an implementable manner of the embodiment of the present invention, the step 302 may specifically include: and placing the substrate in an oxidizing atmosphere for oxidation treatment to obtain a sacrificial material part. Correspondingly, the pretreatment of the substrate in step 301 is a means capable of increasing the oxidation reaction rate of the predetermined region portion of the substrate. The method can be to perform ion implantation in a preset area to improve the oxidation reaction rate of the preset area part of the substrate, or to form a shielding layer with a preset pattern on the substrate to improve the oxidation reaction rate of the preset area part of the substrate.

Of course, in other embodiments, the pretreatment in step 301 may be a means other than an oxidation treatment, and the means may also be to perform ion implantation in a predetermined region to increase the oxidation reaction rate of the predetermined region portion of the substrate, or to form a shielding layer with a predetermined pattern on the substrate to increase the oxidation reaction rate of the predetermined region portion of the substrate.

Step 303, forming a multilayer structure on the sacrificial material layer; the multilayer structure sequentially comprises a lower electrode layer, a piezoelectric layer and an upper electrode layer from bottom to top.

At step 304, the sacrificial material portion is removed to form a resonator.

In this embodiment, the substrate may be a silicon substrate or a substrate made of other materials, which is not limited to this.

According to the resonator manufacturing method, the reaction rate of the preset region part of the substrate is larger than the preset reaction rate corresponding to the non-preset region part by preprocessing the substrate, so that a sacrificial material part in a preset shape can be generated during the preset reaction of the substrate, a multilayer structure is formed on the sacrificial material layer, and finally the sacrificial material part is removed to form the resonator with the special cavity structure.

Referring to fig. 6, an embodiment of the present invention discloses a method for manufacturing a resonator, including the following steps:

step 401, forming a shielding layer on a substrate, wherein the shielding layer covers an area on the substrate except a preset area.

In this step, the process of forming the shielding layer on the substrate may include:

forming a shielding medium on the substrate, wherein the shielding layer is used for shielding the substrate except for a preset region from the preset reaction;

and removing the shielding medium corresponding to the preset area to form the shielding layer.

Wherein the shielding medium acts to make the reaction rate of the portion of the substrate covered with the shielding medium lower than the reaction rate of the portion not covered with the shielding medium. Further, the shielding layer may be used to shield a region of the substrate other than the predetermined region from the predetermined reaction.

Step 402, preprocessing the substrate on which the shielding layer is formed, and controlling a part of the substrate corresponding to the preset area to perform a preset reaction to obtain a sacrificial material part; the sacrificial material portion includes an upper half located above the upper surface of the substrate and a lower half located below the lower surface of the substrate.

Wherein the lower half part is enclosed by a bottom surface and a first side surface; the bottom surface is entirely parallel to the surface of the substrate, and the first side surface is a first smooth curved surface extending from the edge of the bottom wall to the upper surface of the substrate. The upper half part is surrounded by the lower side surface of the multilayer structure, the part of the multilayer structure corresponding to the upper half part comprises a top surface and a second side surface, and the second side surface is a second smooth curved surface extending from the edge of the top surface to the upper surface of the substrate.

Optionally, the first smooth curved surface includes a first curved surface and a second curved surface that are connected in a smooth transition manner. For example, the vertical section of the first curved surface is in an inverted parabolic shape and is located above the plane of the bottom surface; the vertical section of the second curved surface is parabolic and is positioned below the plane of the upper surface of the substrate.

Optionally, the second smooth curved surface includes a third curved surface and a fourth curved surface which are in smooth transition connection; the vertical section of the third curved surface is parabolic and is positioned below the plane of the top surface; the vertical section of the fourth curved surface is in an inverted parabolic shape and is positioned on the plane of the upper surface of the substrate.

As an implementable aspect of the embodiment of the present invention, a curvature of the first smooth curved surface is smaller than a first preset value; and the curvature of the second smooth curved surface is smaller than a second preset value.

As an implementable manner, the implementation of step 402 may include: and placing the substrate in an oxidizing atmosphere for oxidation treatment, and controlling the part of the substrate corresponding to the preset area to perform oxidation reaction to obtain a sacrificial material part.

Wherein, the placing the substrate in an oxidizing atmosphere for oxidation treatment may include:

introducing high-purity oxygen to the substrate in a process temperature environment within a preset range, so that an oxide layer is generated on the part, corresponding to the preset area, of the substrate;

after the first preset time, stopping introducing high-purity oxygen to the substrate, and enabling the thickness of an oxide layer on the substrate to reach a preset thickness through one or more modes of wet oxygen oxidation, oxyhydrogen synthesis oxidation and high-pressure water vapor oxidation;

and stopping introducing the wet oxygen to the substrate and introducing high-purity oxygen to the substrate, and completing the oxidation treatment of the substrate after a second preset time.

Wherein the preset range can be 1000-1200 ℃; the first preset time may be 20 minutes to 140 minutes; the preset thickness can be 0.4-4 μm; the second preset time may be 20 minutes to 140 minutes; the flow rate of the high-purity oxygen can be 3L/min to 15L/min.

It should be noted that, one or a combination of several means of pure oxygen, wet oxygen, hydrogen-oxygen synthesis and high-pressure water vapor oxidation is adopted, the appearance of the transition region has certain difference; meanwhile, the selection of the type and the structure of the shielding layer has certain marketing effect on the appearance of the transition region, and the oxidation mode and the type and the structure of the shielding layer are reasonably selected according to the thickness of the multilayer structure and the requirement of the piezoelectric layer on curvature change.

And 403, removing the pretreated substrate shielding layer.

Step 404, forming a multilayer structure on the substrate after the shielding layer is removed, wherein the multilayer structure sequentially comprises a lower electrode layer, a piezoelectric layer and an upper electrode layer from bottom to top.

At step 405, the sacrificial material portions are removed.

In this embodiment, the shielding layer may be a SiN material layer or SiO layer₂The material layer, the polysilicon material layer, or the multilayer structure formed by mixing the above two or three materials, and the substrate may be a silicon substrate or a substrate made of other materials, which is not limited in this respect.

In one embodiment, the shielding layer may be SiN or may have a multilayer film structure, and SiN is used as the oxidation shielding layer, so that the shielding effect is better, and the reaction rate difference between the shielding region and the non-shielding region is larger. The shielding medium in the area where the resonator needs to be manufactured can be removed by means of etching or corrosion, and the like, the silicon wafer is put in an oxidizing atmosphere for oxidation, and the reaction rate of the part with the shielding medium is larger than that of the part without the shielding medium: the reaction rate of the part without the shielding medium is higher, and the substrate Si reacts with oxygen to form SiO₂SiO produced₂The thickness is increased continuously, the upper surface of the shielding layer is gradually higher than the surface of the shielding medium part, the Si surface of the shielding medium part is gradually lowered, the surface of the shielding medium part is lowered relatively to the surface of the shielding medium part, and oxygen at the edge part of the shielding layer enters the lower part of the shielding layer from the side, so that the oxidation rate of the edge of the shielding layer is slower than that of the shielding medium part and is faster than that of the shielding medium partThe faster the rate, the closer to the edge of the shield dielectric, the more the rate tends to be without the oxidation rate of the shield dielectric portion. A transition region without rate change is formed at the edge of the shielding layer, a smooth curved surface can be formed in the transition region by optimizing an oxidation mode and the type and structure of the shielding layer, and a multi-layer structure of the piezoelectric film containing AlN and the like grows on the smooth curved surface, so that the crystal quality of the piezoelectric film can be ensured.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents or improvements made within the spirit and principle of the present invention should be included in the scope of the present invention.