CN110868175A - Resonator with crystal seed layer, filter and resonator preparation method - Google Patents

Resonator with crystal seed layer, filter and resonator preparation method Download PDF

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Publication number
CN110868175A
CN110868175A CN201910328580.XA CN201910328580A CN110868175A CN 110868175 A CN110868175 A CN 110868175A CN 201910328580 A CN201910328580 A CN 201910328580A CN 110868175 A CN110868175 A CN 110868175A
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substrate
layer
resonator
curved surface
preset
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CN110868175B (en
Inventor
李亮
李丽
吕鑫
梁东升
刘青林
马杰
高渊
丁现朋
冯利东
崔玉兴
张力江
刘相伍
杨志
商庆杰
李宏军
钱丽勋
卜爱民
王强
付兴昌
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CETC 13 Research Institute
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CETC 13 Research Institute
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
    • H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
    • H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02007—Details of bulk acoustic wave devices
    • H03H9/02015—Characteristics of piezoelectric layers, e.g. cutting angles
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02007—Details of bulk acoustic wave devices
    • H03H9/02086—Means for compensation or elimination of undesirable effects
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02007—Details of bulk acoustic wave devices
    • H03H9/02086—Means for compensation or elimination of undesirable effects
    • H03H9/02149—Means for compensation or elimination of undesirable effects of ageing changes of characteristics, e.g. electro-acousto-migration
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
    • H03H9/17—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator
    • H03H9/171—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator implemented with thin-film techniques, i.e. of the film bulk acoustic resonator [FBAR] type
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/46—Filters
    • H03H9/54—Filters comprising resonators of piezoelectric or electrostrictive material
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
    • H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
    • H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
    • H03H2003/023—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks the resonators or networks being of the membrane type
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H2009/02165—Tuning
    • H03H2009/02173—Tuning of film bulk acoustic resonators [FBAR]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

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  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)

Abstract

The invention relates to the technical field of semiconductors, and discloses a resonator with a seed crystal layer, a filter and a resonator preparation method. The resonator includes a substrate; the multilayer structure is formed on the substrate and sequentially comprises a seed crystal layer, a lower electrode layer, a piezoelectric layer and an upper electrode layer from bottom to top; and 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 resonator is provided with the cavity with the lower half cavity and the upper half cavity, the lower half cavity is integrally positioned below the upper surface of the substrate, and the upper half cavity is integrally positioned on the upper surface of the substrate, so that a novel resonator structure with a seed crystal layer is formed, and the resonator structure has better performance.

Description

Resonator with crystal seed layer, filter and resonator preparation method
Technical Field
The invention relates to the technical field of semiconductors, in particular to a resonator with a crystal seed layer, a filter and a resonator preparation method.
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 acoustic reflection structure below the lower electrode, and a substrate below the acoustic reflection 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.
With the development of scientific technology, the requirements on the quality and reliability of acoustic resonators are continuously increased, and higher challenges are provided for better quality resonators, designs and manufacturing methods.
Disclosure of Invention
In view of the above problems, the present invention provides a resonator with a seed layer, a filter and a method for manufacturing the resonator.
A first aspect of an embodiment of the present invention provides a resonator, including:
a substrate;
the multilayer structure is formed on the substrate and sequentially comprises a seed crystal layer, a lower electrode layer, a piezoelectric layer and an upper electrode layer from bottom to top;
and 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.
Optionally, the seed layer has a thickness in a range of 1nm to 1 μm.
Optionally, the seed layer and the piezoelectric layer are formed of the same material.
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 the edge of the bottom wall to the upper surface of the substrate;
the first smooth curved surface comprises a first curved surface and a second curved surface which are in smooth transition connection.
Optionally, the vertical section of the first curved surface is in an inverse parabolic shape and is located on the 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 surrounded by a lower side surface of the multilayer structure, a portion of the multilayer structure corresponding to the upper half cavity is surrounded 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;
the second smooth curved surface comprises a third curved surface and a fourth curved surface which are in smooth transition connection.
Optionally, the vertical section of the third curved surface is parabolic and is located below the 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.
A second aspect of an embodiment of the present invention provides a filter, which is characterized by including any one of the resonators in the first aspect of the embodiment of the present invention.
A third aspect of an embodiment of the present invention provides a method for manufacturing a resonator, where the method includes:
generating a sacrificial material on a substrate, the sacrificial material portion comprising an upper half located above an upper surface of the substrate and a lower half located below a lower surface of the substrate;
forming a multilayer structure on the sacrificial material layer, wherein the multilayer structure sequentially comprises a seed crystal layer, a lower electrode layer, a piezoelectric layer and an upper electrode layer from bottom to top;
and removing the sacrificial material part to form the resonator with a special cavity structure.
Optionally, the generating a sacrificial material on the substrate includes:
preprocessing the substrate, and changing the preset reaction rate of the preset region part of the substrate to enable the preset reaction rate corresponding to the preset region part to be larger than the preset reaction rate corresponding to the non-preset region part;
and carrying out the preset reaction on the substrate to generate a sacrificial material part.
Optionally, the generating a sacrificial material on the substrate includes:
forming a shielding layer on a substrate, wherein the shielding layer covers the region of the substrate except a preset region;
preprocessing the substrate on which the shielding layer is formed, and controlling the part of the substrate corresponding to the preset area to perform preset reaction to obtain a sacrificial material part;
and removing the pretreated substrate shielding layer.
Optionally, the lower half is surrounded 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.
Optionally, the upper half portion is surrounded by a lower side surface of the multilayer structure, a portion of the multilayer structure corresponding to the upper half portion includes a top surface and a second side surface, and the second side surface is a second smooth curved surface extending from an edge of the top surface to an upper surface of the substrate.
Adopt the produced beneficial effect of above-mentioned technical scheme to lie in: according to the embodiment of the invention, the seed crystal layer is arranged in the multilayer structure, the cavity with the lower half cavity and the upper half cavity is simultaneously arranged, the lower half cavity is wholly positioned below the upper surface of the substrate, and the upper half cavity is wholly positioned above the upper surface of the substrate, so that a novel resonator structure is formed, and the resonator has better performance.
Drawings
FIG. 1 is a schematic diagram of a resonator according to one embodiment of the present invention;
FIG. 2 is a schematic diagram of a resonator according to another embodiment of the present invention;
FIG. 3 is an enlarged schematic view of A of FIGS. 1 and 2;
FIG. 4 is a flow chart of a method of making a resonator according to an embodiment of the present invention;
FIG. 5 is a flow chart of another method of fabricating a resonator according to an embodiment of the present invention;
FIG. 6 is a flow chart of yet another method of fabricating a resonator according to an embodiment of the present invention;
fig. 7 is a schematic diagram of a process for manufacturing a resonator according to an embodiment of the invention.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more clearly apparent, the present invention is further described in detail below with reference to the accompanying drawings and 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, an embodiment of the present invention provides a resonator including a substrate 100 and a multi-layer structure 200. The multilayer structure 200 is formed on the substrate 100, and the multilayer structure 200 sequentially includes a seed layer 240, a lower electrode layer 230, a piezoelectric layer 220, and an upper electrode layer 210 from bottom to top. Wherein a cavity 300 is formed between the substrate 100 and the multi-layer structure 200, the cavity 300 comprising a lower half cavity 310 below the upper surface of the substrate 100 and an upper half cavity 320 protruding beyond the upper surface of the substrate 100 and towards the multi-layer structure 200.
In this embodiment, a thin seed layer 240 is formed on the substrate 100 to improve the quality of the piezoelectric layer 220, the seed layer 240 provides a better cushion layer (underlay layer) for forming the piezoelectric layer 220, the piezoelectric layer 220 formed by the seed layer has a characteristic closer to that of a single crystal body than the piezoelectric layer 220 formed by no seed layer, and has a higher quality, and the piezoelectric layer formed by the higher quality forms a higher quality resonator.
Typically, a seed layer 240 is sputtered onto the substrate 100. The seed layer 240 may be composed of aluminum nitride (ALN) or other similar crystalline material, such as aluminum oxynitride (AlON), silicon dioxide (SiO2), silicon nitride (Si3N4), or silicon carbide (SiC).
In one embodiment, the seed layer 240 has a thickness in a range of 1nm to 1 μm.
The process and technique for forming the seed layer 240 is a conventional technique, such as a sputtering technique, and the embodiments of the invention are not limited thereto.
Then, a lower electrode layer 230, a piezoelectric layer 220 and an upper electrode layer 210 are sequentially deposited over the seed layer 240, and the three electrode layers are stacked over the cavity 300. Wherein the upper electrode layer 210 and the lower electrode layer 230 are conductors, such as molybdenum (Mo), and in a simple embodiment, have a thickness in the range of 0.3 microns to 0.5 microns. The piezoelectric layer 220 is typically comprised of a crystal, such as aluminum nitride, and in a simple embodiment has a thickness in the range of 0.5 microns to 1.0 microns. Without limitation, the present invention is not limited to these materials and dimensional ranges.
In one embodiment, the seed layer 240 and the piezoelectric layer 220 are composed of the same material, namely aluminum nitride (ALN). The seed layer 240 forms the lower electrode layer 230 into a smoother, more uniform nodule, and the lower electrode layer 230 promotes the material of the piezoelectric layer 220 to be closer to single crystal quality, increasing the piezoelectric coupling constant of the piezoelectric layer 220, thereby enabling the fabrication of a wider bandwidth electrical filter with a resonator.
Meanwhile, the seed crystal layer 240 also plays a role of a protective pad layer, and since the lower electrode 230 is a metal conductor, it is very easy to generate a chemical reaction with air and water vapor and be oxidized, thereby affecting the stability of the resonant frequency of the resonator, and the seed crystal layer 240 can protect the lower electrode layer 230 from the air and water vapor in the environment.
Referring to fig. 1, in one embodiment, the lower half cavity 310 is surrounded by a bottom wall 101 and a first sidewall 102, the bottom wall 101 is entirely parallel to the surface of the substrate 100, and the first sidewall 102 is a first rounded curved surface extending from an edge of the bottom wall 101 to the upper surface of the substrate 100.
Wherein, the bottom wall 101 and the first sidewall 102 are both surface walls of the substrate 100. The first side wall 102 is a first smooth curved surface, which can ensure the performance of the resonator cavity without sudden change.
Referring to fig. 3, in one embodiment, 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. Wherein the substrate 100 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 surface should not be too large to affect the performance of the resonator.
For example, the vertical section of the first curved surface 1021 may be an inverted parabola shape and is located above the plane of the bottom wall 101; the vertical cross-section of the second curved surface 1022 may be parabolic and is located below the plane of the upper surface of the substrate 100. 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.
In one embodiment, the first round curved surface is smooth as a whole, and the curvature of each point of the first round curved surface 1021 may be smaller than a first preset value. The first preset value can be set according to actual conditions so as to achieve the purpose that gaps among the crystals at the first smooth curved surface do not affect the performance of the resonator. In order to ensure the mechanical and electrical properties of the multilayer structure, the curvature of the smooth curved surface of the transition region is as small as possible, and under the condition that the thickness of the sacrificial layer is constant, the smallest curvature requires that the length of the transition region is increased, which increases the area of the resonator, so the curvature of the transition region and the length of the transition region are optimized. Preferably, the thickness of the cavity 300 may be 1 μm, and the length of the transition region is controlled to be 3 μm to 5 μm, and the multilayer structure grown in the transition region can satisfy the resonator requirement. The transition zone length is the length of the first sidewall 102 in the direction of the dashed line shown in fig. 1.
Referring to fig. 1, in one embodiment, the upper cavity half 302 may be surrounded by the lower side of the multi-layer structure 200, and a portion of the lower side of the multi-layer structure 200 corresponding to the upper cavity half 302 includes a top wall 201 and a second side wall 202, and the second side wall 202 is a second rounded surface extending from an edge of the top wall 201 to the upper surface of the substrate 100.
Wherein, the top wall 201 and the second side wall 202 are both lower side walls of the multi-layer structure 200. The second sidewall 202 is a second smooth curved surface, which can ensure the performance of the resonator cavity without sudden change.
Referring to fig. 3, in one embodiment, the second rounded curved surface may include a third curved surface 2021 and a fourth curved surface 2022 that are rounded to transition. 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. Wherein, from the crystal perspective, the substrate 100 is composed of many crystals (e.g. silicon crystals), and the absence of abrupt change means that the gap between the respective crystals at the second rounded curved surface should not be too large to affect the performance of the resonator.
For example, the vertical section of the third curved surface 2021 may be parabolic and is located below the plane of the top wall 201; 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 100. 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.
In one embodiment, the curvature of each point of the second rounded surface 2021 is less than a second predetermined value. The second preset value can be set according to actual conditions so as to achieve the purpose that gaps among the crystals at the second round curved surface do not affect the performance of the resonator.
Further, the top wall 201 also has no abrupt change. The abrupt changes described here are consistent with the aforementioned abrupt changes, and from a crystal standpoint, the multilayer structure 200 is also comprised of many crystals, and the absence of abrupt changes means that the gaps between the individual crystals at the top wall 201 should not be too large to affect the performance of the resonator.
Referring to fig. 2, in one embodiment, the resonator further includes a protective layer 250 disposed over the upper electrode layer 210, the protective layer 250 covering at least the upper electrode layer 210. Since the upper electrode layer 210 is a conductive metal, long-term exposure to the environment may cause oxidation due to contact with air and water vapor, and the oxidation may change the mass of the electrode, thereby changing the resonant frequency of the resonator, causing the resonant frequency to shift. In order to reduce or minimize the shift of the resonant frequency and to ensure the stability of the resonant frequency of the resonator, a protective layer 250 is disposed over the upper electrode layer 210 to protect the upper electrode from air and moisture.
The protective layer 250 is generally made of an inert material that does not easily interact with the environment, such as aluminum oxynitride (AlON), silicon dioxide (SiO2), silicon nitride (Si3N4), or silicon carbide (SiC). In the present embodiment, the thickness of the passivation layer 250 ranges from 30 angstroms to 2 microns, and the passivation layer 250 can also be formed of silicon nitride, and silicon nitride can also be used for the piezoelectric layer 220.
Meanwhile, the electrical quality factor (Q) of the resonator may also be optimized by adjusting the thickness of the protective layer 250.
In the above embodiments, the substrate 100 may be a silicon substrate or a substrate made of other materials, which is not limited to this.
In the resonator, the seed layer 240 is arranged in the multilayer structure, so that a higher-quality resonator can be constructed, and the cavity 300 with the lower half cavity 310 and the upper half cavity 320 is arranged at the same time, the lower half cavity 310 is wholly positioned below the upper surface of the substrate 100, and the upper half cavity 320 is wholly positioned above the upper surface of the substrate 100, so that a novel resonator structure is formed, and the resonator has better performance.
Referring to fig. 4, an embodiment of the present invention discloses a method for manufacturing a resonator, including the following steps:
step 401, a sacrificial material is generated on a substrate, wherein the sacrificial material comprises an upper half portion located above an upper surface of the substrate and a lower half portion located below a lower surface of the substrate.
Step 402, forming a multilayer structure on the sacrificial material layer, wherein the multilayer structure comprises a seed layer, a lower electrode layer, a piezoelectric layer and an upper electrode layer from bottom to top.
In step 403, the sacrificial material is removed to form a resonator with a special cavity structure.
Referring to fig. 5, an embodiment of the present invention discloses a method for manufacturing a resonator, including the following steps:
step 501, a substrate is preprocessed, and a preset reaction rate of a preset region part of the substrate is changed, 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 can be made to be different when the preset reaction is performed on the substrate in the subsequent step 502, and the sacrificial material portion in the preset shape is generated.
Step 502, 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.
Optionally, the lower half is surrounded 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.
Optionally, the upper half portion is surrounded by a lower side surface of the multilayer structure, a portion of the multilayer structure corresponding to the upper half portion includes a top surface and a second side surface, and the second side surface is a second smooth curved surface extending from an edge of the top surface to an 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.
In one embodiment, the curvature of the first round 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.
In one embodiment, the step 302 may be implemented by: 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 503, forming a multilayer structure on the sacrificial material layer; the multilayer structure sequentially comprises a seed crystal layer, a lower electrode layer, a piezoelectric layer and an upper electrode layer from bottom to top.
And step 504, removing the sacrificial material part to form a resonator with a special cavity structure.
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 601, forming a shielding layer on the substrate, wherein the shielding layer covers the substrate except for the preset area, which is shown in fig. 7 (a).
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 602, preprocessing the substrate on which the shielding layer is formed, and controlling a part of the substrate corresponding to the preset region 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.
In one embodiment, the curvature of the first round 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 implementation manner, the implementation process of step 602 may include: and (c) placing the substrate in an oxidizing atmosphere to perform oxidation treatment, and controlling a part of the substrate corresponding to the preset area to perform oxidation reaction to obtain a sacrificial material part, as shown in fig. 7 (b).
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.
Step 603, removing the pretreated substrate shielding layer, see fig. 7 (c).
Step 604, forming a multilayer structure on the substrate after the shielding layer is removed, wherein the multilayer structure sequentially comprises a seed layer, a lower electrode layer, a piezoelectric layer and an upper electrode layer from bottom to top, as shown in fig. 7 (d).
At step 605, the sacrificial material portion is removed to form a resonator with a special cavity structure, see fig. 7 (e).
In this embodiment, the shielding layer may be a SiN material layer, a SiO2 material layer, a polysilicon material layer, or a multilayer structure formed by mixing 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 can beSiN can also be in a multilayer film structure, the SiN is used as an oxidation shielding layer, the shielding effect is good, and the reaction rate difference between the shielding region and the non-shielding region is large. 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, and the surface of the shielding medium part is lowered relatively. 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 embodiment of the invention also discloses a semiconductor device which comprises any one of the resonators and has the beneficial effects of the resonators. For example, the semiconductor device may be a filter.
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 and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims (13)

1. A resonator, comprising:
a substrate;
the multilayer structure is formed on the substrate and sequentially comprises a seed crystal layer, a lower electrode layer, a piezoelectric layer and an upper electrode layer from bottom to top;
and 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.
2. The resonator of claim 1, wherein the seed layer thickness ranges from 1nm to 1 μ ι η.
3. The resonator of claim 1, wherein the seed layer and the piezoelectric layer are formed of a same material.
4. The resonator according to any of claims 1 to 3, characterized in that 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 rounded curved surface extending from the edge of the bottom wall to the upper surface of the substrate;
the first smooth curved surface comprises a first curved surface and a second curved surface which are in smooth transition connection.
5. The resonator according to claim 4, characterized in that the vertical section of the first curved surface is in the shape of an inverted parabola and is located above 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.
6. The resonator according to any of claims 1 to 3, characterized in that the upper half cavity is enclosed by a lower side of the multilayer structure, a portion of the multilayer structure corresponding to the upper half cavity is enclosed by a top wall and a second side wall, and the second side wall is a second rounded surface extending from an edge of the top wall to an upper surface of the substrate;
the second smooth curved surface comprises a third curved surface and a fourth curved surface which are in smooth transition connection.
7. The resonator according to claim 6, characterized in that the vertical section of said third curved surface is parabolic and is located below the plane of said 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.
8. A filter comprising a resonator according to any of claims 1 to 7.
9. A method of making a resonator, the method comprising:
generating a sacrificial material on a substrate, the sacrificial material portion comprising an upper half located above an upper surface of the substrate and a lower half located below a lower surface of the substrate;
forming a multilayer structure on the sacrificial material layer, wherein the multilayer structure sequentially comprises a seed crystal layer, a lower electrode layer, a piezoelectric layer and an upper electrode layer from bottom to top;
and removing the sacrificial material part to form the resonator with a special cavity structure.
10. The method of claim 9, wherein the forming a sacrificial material on a substrate comprises:
preprocessing the substrate, and changing the preset reaction rate of the preset region part of the substrate to enable the preset reaction rate corresponding to the preset region part to be larger than the preset reaction rate corresponding to the non-preset region part;
and carrying out the preset reaction on the substrate to generate a sacrificial material part.
11. The method of claim 9, wherein the forming a sacrificial material on a substrate comprises:
forming a shielding layer on a substrate, wherein the shielding layer covers the region of the substrate except a preset region;
preprocessing the substrate on which the shielding layer is formed, and controlling the part of the substrate corresponding to the preset area to perform preset reaction to obtain a sacrificial material part;
and removing the pretreated substrate shielding layer.
12. The method of claim 9, wherein the lower half is surrounded 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.
13. The method of claim 9, wherein the upper half is surrounded by a lower side of the multi-layer structure, and a portion of the multi-layer structure corresponding to the upper half comprises a top surface and a second side surface, and the second side surface is a second rounded surface extending from an edge of the top surface to an upper surface of the substrate.
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CN107863948A (en) * 2016-09-21 2018-03-30 三星电机株式会社 Acoustic resonator and the wave filter including the acoustic resonator
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CN1472884A (en) * 2002-07-30 2004-02-04 ƽ Improved resonator with seed layer
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