CN110868175B - Resonator with seed layer, filter and resonator preparation method - Google Patents
Resonator with seed layer, filter and resonator preparation method Download PDFInfo
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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
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- 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
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- 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
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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
- 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
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- 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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- Acoustics & Sound (AREA)
- Engineering & Computer Science (AREA)
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- 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 preparation method of the resonator. The resonator includes a substrate; the multilayer structure is formed on the substrate and comprises a seed crystal layer, a lower electrode layer, a piezoelectric layer and an upper electrode layer from bottom to top in sequence; wherein a cavity is formed between the substrate and the multilayer structure, the cavity including a lower cavity half below the upper surface of the substrate and an upper cavity half above the upper surface of the substrate and protruding toward the multilayer structure. The resonator is provided with the cavity with the lower half cavity and the upper half cavity, the whole lower half cavity is positioned below the upper surface of the substrate, and the whole upper half cavity is positioned above the upper surface of the substrate, so that a novel resonator structure with a seed crystal layer is formed, and the novel resonator structure has better performance.
Description
Technical Field
The present invention relates to the field of semiconductor technology, and in particular, to a resonator with a seed crystal layer, a filter, and a method for manufacturing the resonator.
Background
Resonators may be used in a variety of 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 the application, 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 positioned between the upper and lower electrodes, an acoustic reflecting structure positioned below the lower electrode, and a substrate positioned below the acoustic reflecting structure. The region where the three layers of materials of the upper electrode, the piezoelectric layer, and the lower electrode overlap in the thickness direction is generally defined as the effective region of the resonator. When a voltage signal with a certain frequency is applied between the electrodes, sound waves which propagate in the vertical direction can be generated between the upper electrode and the lower electrode in the effective area due to the inverse piezoelectric effect of the piezoelectric material, and the sound waves are reflected back and forth between the interface between the upper electrode and the air and the sound reflection structure under the lower electrode and resonate at a certain frequency.
With the development of scientific technology, the requirements on the quality and reliability of acoustic resonators are continually increasing, and higher challenges are presented to more quality resonators, designs and manufacturing methods.
Disclosure of Invention
Based on 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 comprises a seed crystal layer, a lower electrode layer, a piezoelectric layer and an upper electrode layer from bottom to top in sequence;
wherein a cavity is formed between the substrate and the multilayer structure, the cavity including a lower cavity half below the upper surface of the substrate and an upper cavity half above the upper surface of the substrate and protruding toward the multilayer structure.
Optionally, the thickness of the seed crystal layer is in the range of
To->
。
Optionally, the seed layer and the piezoelectric layer are formed of the same material.
Optionally, the lower half cavity is surrounded 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;
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 inverted parabolic shape and is positioned above the plane where the bottom wall is positioned;
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 includes a top wall and a second side wall, and the second side wall is a second smooth curved surface extending from the edge of the top wall to the 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 above the plane where the upper surface of the substrate is positioned.
A second aspect of an embodiment of the present invention provides a filter, which is characterized by comprising any one of the resonators of 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, the method including:
generating a sacrificial material on a substrate, the sacrificial material portion comprising an upper half above an upper surface of the substrate and a lower half 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 the special cavity structure.
Optionally, the generating the sacrificial material on the substrate includes:
pretreating the substrate, and changing the preset reaction rate of the preset area part of the substrate so that the preset reaction rate corresponding to the preset area part is larger than the preset reaction rate corresponding to the non-preset area part;
and carrying out the preset reaction on the substrate to generate a sacrificial material part.
Optionally, the generating the sacrificial material on the substrate includes:
forming a shielding layer on a substrate, wherein the shielding layer covers an area except a preset area on the substrate;
preprocessing a substrate on which a 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;
and removing the pretreated substrate shielding layer.
Optionally, the lower half is surrounded by a bottom surface and a first side surface; the whole bottom surface is 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 part is surrounded by the lower side surface of the multilayer structure, a portion of the multilayer structure corresponding to the upper half part includes 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.
The beneficial effects of adopting above-mentioned technical scheme to produce lie in: according to the embodiment of the invention, the seed crystal layer is arranged in the multilayer structure, and the cavity with the lower half cavity and the upper half cavity is arranged at the same time, 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 an embodiment of the invention;
FIG. 2 is a schematic diagram of a resonator according to another embodiment of the invention;
FIG. 3 is an enlarged schematic view of A in FIGS. 1 and 2;
FIG. 4 is a flow chart of a method of fabricating a resonator according to an embodiment of the invention;
FIG. 5 is a flow chart of yet another method of fabricating a resonator according to an embodiment of the invention;
FIG. 6 is a flow chart of yet another method of fabricating a resonator according to an embodiment of the invention;
fig. 7 (a) -7 (e) are schematic views illustrating a manufacturing process of a resonator according to an embodiment of the invention.
Detailed Description
In order to make the technical problems, technical schemes and beneficial effects to be solved more clear, the 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 for purposes of illustration only and are not intended to limit the scope of the invention.
The invention will be described in further detail with reference to the drawings and the detailed description.
Referring to fig. 1, an embodiment of the present invention provides a resonator including a substrate 100 and a multilayer structure 200. The multilayer structure 200 is formed on the substrate 100, and the multilayer structure 200 includes a seed layer 240, a lower electrode layer 230, a piezoelectric layer 220, and an upper electrode layer 210 in this order from bottom to top. Wherein a cavity 300 is formed between the substrate 100 and the multilayer structure 200, the cavity 300 comprising a lower cavity half 301 below the upper surface of the substrate 100 and an upper cavity half 302 protruding beyond the upper surface of the substrate 100 and towards the multilayer structure 200.
In this embodiment, a thin seed layer 240 is formed on the substrate 100 to enhance the quality of the piezoelectric layer 220, the seed layer 240 provides a better underlayer (underlayer) for forming the piezoelectric layer 220, the piezoelectric layer 220 formed with the seed layer has a property closer to single crystal than the piezoelectric layer 220 formed without the seed layer, and the piezoelectric layer with the higher quality is formed to form a resonator with higher quality.
Typically, seed layer 240 is sputtered onto 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 (SiO 2), silicon nitride (Si 3N 4), or silicon carbide (SiC), among others.
In one embodiment, the thickness of the seed layer 240 ranges from
To->
。
The process and technique of constructing seed layer 240 is well known in the art, such as sputtering, and embodiments of the present invention are not limited in this regard.
Then, a lower electrode layer 230, a piezoelectric layer 220 and an upper electrode layer 210 are sequentially deposited over the seed layer 240, with three electrode layers stacked over the cavity 300. Wherein the upper electrode layer 210 and the lower electrode layer 230 are conductors, such as molybdenum (Mo), in a simple embodiment, the thickness ranges from 0.3 microns to 0.5 microns. The piezoelectric layer 220 is typically composed 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 size ranges.
In one embodiment, seed layer 240 and piezoelectric layer 220 are composed of the same material, aluminum nitride (ALN). The seed layer 240 causes the lower electrode layer 230 to be more smoothly and uniformly shaped, and the lower electrode layer 230 promotes the material of the piezoelectric layer 220 to be more similar to single crystal quality, and increases the piezoelectric coupling constant of the piezoelectric layer 220, thereby enabling the fabrication of a wider bandwidth electrical filter using a resonator.
Meanwhile, the seed layer 240 also plays a role of a protection cushion layer, and since the lower electrode 230 is a metal conductor, chemical reaction with air and water vapor is very easy to occur and oxidized, so that the stability of the resonance frequency of the resonator is affected, and the seed layer 240 can protect the lower electrode 230 from the air and water vapor in the environment.
Referring to fig. 1, in one embodiment, the lower half cavity 301 is surrounded by a bottom wall 101 and a first side wall 102, the bottom wall 101 is parallel to the surface of the substrate 100, and the first side wall 102 is a first rounded surface extending from the edge of the bottom wall 101 to the upper surface of the substrate 100.
Wherein the bottom wall 101 and the first side wall 102 are both surface walls of the substrate 100. The first sidewall 102 is a first rounded surface, which can ensure the performance of the resonator cavity without abrupt change.
Referring to fig. 3, in one embodiment, the first rounded curved surface may include a first curved surface 1021 and a second curved surface 1022 that are connected by a rounded transition. The first curved surface 1021 and the second curved surface 1022 in smooth transition connection means that the connection part between the first curved surface 1021 and the second curved surface 1022 is free from mutation, and both the first curved surface 1021 and the second curved surface 1022 are also free from mutation, so that the performance of the resonator cavity can be ensured. Wherein the substrate 100 is composed of a plurality of crystals (e.g., silicon crystals), no abrupt change means that the gaps between the 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 inverted parabolic and located above the plane of the bottom wall 101; the second curved surface 1022 may have a parabolic vertical cross-section and may be 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 of other shapes, so long as the gaps between the crystals at the first rounded curved surface do not affect the performance of the resonator.
In one embodiment, the first rounded surface is smooth as a whole, and the curvature of each point of the first rounded surface may be smaller than a first preset value. The first preset value can be set according to practical situations, so that the purpose that gaps among crystals at the first smooth curved surface do not influence the performance of the resonator is achieved. 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 the minimum curvature requires the length of the transition region to be increased under the condition of a certain thickness of the sacrificial layer, so that the area of the resonator is increased, and therefore, 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, the length of the transition region is controlled to be 3 μm to 5 μm, and the multi-layer structure grown in the transition region can meet resonator requirements. 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 302 may be surrounded by a lower side of the multi-layer structure 200, where a portion of the lower side of the multi-layer structure 200 corresponding to the upper cavity 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 an 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 side wall 202 is a second smooth curved surface, which can ensure the performance of the resonator cavity without abrupt change.
Referring to fig. 3, in one embodiment, the second rounded surface may include a third surface 2021 and a fourth surface 2022 that are rounded. The third curved surface 2021 and the fourth curved surface 2022 that are in smooth transition connection mean that the connection position between the third curved surface 2021 and the fourth curved surface 2022 is free from mutation, and both the third curved surface 2021 and the fourth curved surface 2022 are also free from mutation, so that the performance of the resonator cavity can be ensured. Wherein from a crystal point of view, the substrate 100 is composed of a plurality of crystals (e.g., silicon crystals), and no abrupt change means that the gaps between the crystals at the second rounded 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 located below the plane of the top wall 201; the vertical section of the fourth curved surface 2022 is inverted parabolic 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 it is sufficient that the gaps between the crystals at the first rounded curved surface do not affect the performance of the resonator.
In one embodiment, the curvature of each point of the second rounded curved surface is smaller than a second preset value. The second preset value can be set according to practical situations, so that the purpose that gaps among crystals at the second smooth curved surface do not influence the performance of the resonator is achieved.
Further, the top wall 201 is also free of abrupt parts. The abrupt changes described herein are consistent with the foregoing abrupt changes, and from a crystal standpoint, the multilayer structure 200 is also composed of a plurality of crystals, with no abrupt changes meaning 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, oxidation occurs due to contact with air and moisture in the environment for a long period of time, and oxidation changes the mass of the electrode, thereby changing the resonant frequency of the resonator and causing a drift in the resonant frequency. In order to reduce or minimize the resonance frequency drift, to ensure the stability of the resonance frequency of the resonator, a protective layer 250 is provided over the upper electrode layer 210, protecting the upper electrode from air and moisture.
The protective layer 250 is generally made of an inert material that is not easily reactive with the environment, such as aluminum oxynitride (AlON), silicon dioxide (SiO 2), silicon nitride (Si 3N 4), or silicon carbide (SiC). In this embodiment, the thickness of the protective layer 250 ranges from 30 a to 2 μm, and the protective layer 250 may be made of silicon nitride material, and silicon nitride may be used for the piezoelectric layer 220.
Meanwhile, the thickness of the protective layer 250 can be adjusted to optimize the electrical quality factor of the resonator
)。
In the above embodiment, the substrate 100 may be a silicon substrate or a substrate made of other materials, which is not limited thereto.
In the above resonator, by disposing the seed layer 240 in the multilayer structure, a resonator of higher quality can be constructed, and simultaneously, the cavity 300 having the lower half cavity 301 and the upper half cavity 302 is disposed, and the lower half cavity 301 is integrally located below the upper surface of the substrate 100, and the upper half cavity 302 is integrally located above the upper surface of the substrate 100, thereby forming a novel resonator structure, so that the resonator has better performance.
Referring to fig. 4, in one embodiment of the present invention, a method for manufacturing a resonator is disclosed, including the steps of:
A multi-layer structure is formed on the sacrificial material layer, the multi-layer structure including, in order from bottom to top, a seed layer, a lower electrode layer, a piezoelectric layer, and an upper electrode layer, step 402.
Referring to fig. 5, in one embodiment of the present invention, a method for manufacturing a resonator is disclosed, including the steps of:
In this step, the preset reaction rate of the preset area portion of the substrate is enabled to reach the effect that the preset reaction rate corresponding to the preset area portion is greater than the preset reaction rate corresponding to the non-preset area portion by performing the pretreatment on the preset area portion of the substrate, so that when the preset reaction is performed on the substrate in the subsequent step 502, the reaction rate of the preset area portion and the reaction rate of the non-preset area portion are enabled to be different, so as to generate the sacrificial material portion with the preset shape.
Optionally, the lower half is surrounded by a bottom surface and a first side surface; the whole bottom surface is 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 part is surrounded by the lower side surface of the multilayer structure, a portion of the multilayer structure corresponding to the upper half part includes 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 comprises 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 above the plane where the bottom surface is positioned; 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 comprises 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 where the top surface is positioned; the vertical section of the fourth curved surface is in an inverted parabolic shape and is positioned above the plane where the upper surface of the substrate is positioned.
In one embodiment, the curvature of the first smooth curved surface is smaller than a first preset value; the curvature of the second smooth curved surface is smaller than a second preset value.
It can be appreciated that, since the preset reaction rate corresponding to the preset region portion is greater than the preset reaction rate corresponding to the non-preset region portion, when the preset reaction is performed on the substrate, the preset region portion reacts fast and the non-preset region portion reacts slow, so that the sacrificial material portion of the preset shape can be generated.
In one embodiment, the implementation of step 502 may include: and (3) placing the substrate in an oxidizing atmosphere for oxidation treatment to obtain the sacrificial material part. Correspondingly, the pretreatment of the substrate in step 501 is a means capable of increasing the oxidation reaction rate of the predetermined area portion of the substrate. The means may be ion implantation in the preset area to increase the oxidation reaction rate of the preset area portion of the substrate, or may be a shielding layer with a preset pattern formed on the substrate to increase the oxidation reaction rate of the preset area portion of the substrate.
Of course, in other embodiments, the pretreatment in step 501 may be other than oxidation treatment, and the method may be to perform ion implantation in the preset area to increase the oxidation reaction rate of the preset area portion of the substrate, or to form a shielding layer with a preset pattern on the substrate to increase the oxidation reaction rate of the preset area portion of the substrate.
At step 504, the sacrificial material portions are removed to form a resonator having a particular cavity structure.
In this embodiment, the substrate may be a silicon substrate or a substrate made of other materials, which is not limited thereto.
According to the method for manufacturing the resonator, the reaction rate of the preset area part of the substrate is larger than the corresponding preset reaction rate of the non-preset area part by preprocessing the substrate, so that the sacrificial material part with the preset shape can be generated when the substrate is subjected to the preset reaction, a multi-layer 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, and compared with the traditional manufacturing method, the surface roughness of the working area of the resonator is easier to control.
Referring to fig. 6, an embodiment of the invention discloses a method for manufacturing a resonator, which comprises the following steps:
in step 601, a shielding layer is formed on a substrate, the shielding layer covering an area other than a predetermined area on the substrate, see 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 area of the substrate except for a preset area from the preset reaction;
and removing the shielding medium corresponding to the preset area to form the shielding layer.
Wherein the shielding medium acts such that the reaction rate of the portion of the substrate covered by the shielding medium is lower than the reaction rate of the portion not covered by the shielding medium. Further, the shielding layer may be used to shield the substrate from the preset reaction in an area other than the preset area.
Wherein the lower half part is surrounded by a bottom surface and a first side surface; the whole bottom surface is 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 in smooth transition connection. For example, the vertical section of the first curved surface is in an inverted parabolic shape and is positioned 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 comprises 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 where the top surface is positioned; the vertical section of the fourth curved surface is in an inverted parabolic shape and is positioned above the plane where the upper surface of the substrate is positioned.
In one embodiment, the curvature of the first smooth curved surface is smaller than a first preset value; 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 (3) 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, as shown in fig. 7 (b).
Wherein, the placing the substrate in an oxidizing atmosphere for oxidation treatment may include:
introducing high-purity oxygen into the substrate in a process temperature environment in a preset range so as to enable an oxide layer to be generated on the substrate at a part corresponding to the preset area;
after a 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 by one or more modes of wet oxygen oxidation, oxyhydrogen synthesis oxidation and high-pressure water vapor oxidation;
and stopping introducing wet oxygen into the substrate and introducing high-purity oxygen into the substrate, and finishing 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 may be 0.4 μm to 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-15L/min.
It should be noted that, the shape of the transition area has a certain difference by adopting one or a combination of several means of pure oxygen, wet oxygen, oxyhydrogen synthesis and high-pressure water vapor oxidation; meanwhile, the type and structure of the shielding layer are selected, a certain marketing is provided for the shape of the transition region, and the oxidation mode and the type and 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.
In step 604, a multi-layer structure is formed on the substrate after the shielding layer is removed, wherein the multi-layer structure includes a seed layer, a lower electrode layer, a piezoelectric layer and an upper electrode layer in order from bottom to top, see fig. 7 (d).
In this embodiment, the shielding layer may be a SiN material layer, a SiO2 material layer, a polysilicon material layer, or a multi-layer 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 one embodiment, the shielding layer can be SiN or a multilayer film structure, siN is used as an oxidation shielding layer, the shielding effect is good, and the reaction rate of the shielding region and the non-shielding region is large. The shielding medium needed to manufacture the resonator area can be removed by means of etching or corrosion, the silicon wafer is put in an oxidizing atmosphere for oxidation, and the reaction rate of the part with the shielding medium and the reaction rate of the part without the shielding medium are greatly different: without any means for holdingThe reaction rate of the part with the shielding medium is faster, and the substrate Si reacts with oxygen to form SiO 2 SiO produced 2 The thickness is increased gradually, the upper surface of the shielding layer is increased gradually than the surface with the shielding medium part, the Si surface without the shielding medium part is decreased gradually, and the surface without the shielding medium part is decreased relatively, and as oxygen at the edge part of the shielding layer can enter the lower part of the shielding layer from the side surface, the oxidation rate of the edge of the shielding layer is slower than that of the part without the shielding medium part, the oxidation rate of the edge of the shielding layer is faster than that of the part with the shielding medium part, and the closer to the edge of the shielding medium, the oxidation rate of the part without the shielding medium tends to be higher. And forming a transition region without rate change at the edge of the shielding layer, wherein the transition region can form a smooth curved surface by optimizing the oxidation mode and the type and structure of the shielding layer, and a multilayer structure of the pressure-equal-voltage thin film containing AlN is grown on the smooth curved surface, so that the crystal quality of the piezoelectric thin film can be ensured.
The embodiment of the invention also discloses a semiconductor device which comprises any resonator and has the beneficial effects of the resonator. For example, the semiconductor device may be a filter.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.
Claims (6)
1. A resonator, comprising:
a substrate;
the multilayer structure is formed on the substrate and comprises a seed crystal layer, a lower electrode layer, a piezoelectric layer and an upper electrode layer from bottom to top in sequence;
wherein a cavity is formed between the substrate and the multilayer structure, the cavity comprising a lower half cavity below the upper surface of the substrate and an upper half cavity protruding beyond the upper surface of the substrate and toward the multilayer structure;
the seed layer and the piezoelectric layer are formed of the same material;
the lower half cavity is surrounded 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; the curvature of each point of the first smooth curved surface is smaller than a first preset value;
the first smooth curved surface comprises 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 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;
the upper half cavity is surrounded by 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 extending from the edge of the top wall to the upper surface of the substrate; the curvature of each point of the second smooth curved surface is smaller than a second preset value;
the second smooth curved surface comprises 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 where the top wall is positioned; the vertical section of the fourth curved surface is in an inverted parabolic shape and is positioned above the plane where the upper surface of the substrate is positioned.
2. The resonator according to claim 1, characterized in that the seed layer thickness is in the range of
To->
。
3. A filter comprising a resonator as claimed in any one of claims 1 to 2.
4. A method of manufacturing a resonator, the method comprising:
generating a sacrificial material on a substrate, the sacrificial material portion comprising an upper half above an upper surface of the substrate and a lower half 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;
removing the sacrificial material portion to form a resonator having a special cavity structure;
wherein the seed layer and the piezoelectric layer are formed of the same material;
the lower half part is surrounded by a bottom surface and a first side surface; the whole bottom surface is 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 surface to the upper surface of the substrate; the curvature of each point of the first smooth curved surface is smaller than a first preset value;
the first smooth curved surface comprises 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 above the plane where the bottom surface is positioned; the vertical section of the second curved surface is parabolic and is positioned below the plane of 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; the curvature of each point of the second smooth curved surface is smaller than a second preset value;
the second smooth curved surface comprises 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 where the top surface is positioned; the vertical section of the fourth curved surface is in an inverted parabolic shape and is positioned above the plane where the upper surface of the substrate is positioned.
5. The method of manufacturing a resonator according to claim 4, wherein the generating a sacrificial material on the substrate comprises:
pretreating the substrate, and changing the preset reaction rate of the preset area part of the substrate so that the preset reaction rate corresponding to the preset area part is larger than the preset reaction rate corresponding to the non-preset area part;
and carrying out the preset reaction on the substrate to generate a sacrificial material part.
6. The method of manufacturing a resonator according to claim 4, wherein the generating a sacrificial material on the substrate comprises:
forming a shielding layer on a substrate, wherein the shielding layer covers an area except a preset area on the substrate;
preprocessing a substrate on which a 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;
and removing the pretreated substrate shielding layer.
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| CN1472884A (en) * | 2002-07-30 | 2004-02-04 | ƽ | Improved resonator with inoculation layer |
| CN101465628A (en) * | 2009-01-15 | 2009-06-24 | 电子科技大学 | Film bulk acoustic wave resonator and preparation method thereof |
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| JP5710153B2 (en) * | 2010-05-11 | 2015-04-30 | 日本信号株式会社 | Method for manufacturing piezoelectric element |
| CN103532516B (en) * | 2013-08-05 | 2017-10-24 | 天津大学 | Body wave resonator and its manufacture method |
| US9374059B1 (en) * | 2015-01-06 | 2016-06-21 | Zhuhai Advanced Chip Carriers & Electronic Substrate Solutions Technologies Co. Ltd. | Film bulk acoustic resonator filter |
| KR101867285B1 (en) * | 2016-09-21 | 2018-07-19 | 삼성전기주식회사 | Acoustic Wave Resonator And Filter including the Same |
| US10715099B2 (en) * | 2016-10-28 | 2020-07-14 | Samsung Electro-Mechanics Co., Ltd. | Bulk acoustic wave resonator and method for manufacturing the same |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1472884A (en) * | 2002-07-30 | 2004-02-04 | ƽ | Improved resonator with inoculation layer |
| CN101465628A (en) * | 2009-01-15 | 2009-06-24 | 电子科技大学 | Film bulk acoustic wave resonator and preparation method thereof |
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