CN110113703B - Preparation method of MEMS structure - Google Patents

Preparation method of MEMS structure Download PDF

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CN110113703B
CN110113703B CN201910415713.7A CN201910415713A CN110113703B CN 110113703 B CN110113703 B CN 110113703B CN 201910415713 A CN201910415713 A CN 201910415713A CN 110113703 B CN110113703 B CN 110113703B
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layer
piezoelectric
substrate
electrode layer
groove
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CN110113703A (en
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刘端
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Anhui Aofei Acoustics Technology Co ltd
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Anhui Aofei Acoustics Technology Co ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R31/00—Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor
    • H04R31/003—Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor for diaphragms or their outer suspension
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2231/00—Details of apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor covered by H04R31/00, not provided for in its subgroups
    • H04R2231/001—Moulding aspects of diaphragm or surround

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

Abstract

The application discloses a method of fabricating a MEMS (micro-electro-mechanical system) structure, comprising: etching a plurality of parallel second grooves in the peripheral area on the front surface of the substrate, and depositing a piezoelectric composite vibration layer on the substrate, wherein the piezoelectric composite vibration layer formed on the bottom and the side wall of the second grooves forms a first corrugated part; depositing a mass block in the middle area of the piezoelectric composite vibration layer; etching the exposed substrate to form a first groove outside the piezoelectric composite vibration layer; and etching the back surface of the substrate to form a cavity, wherein a first groove is adjacently arranged at the periphery of the cavity, and the piezoelectric composite vibration layer is formed right above the cavity, wherein the substrate at the part between the first groove and the cavity supports the piezoelectric composite vibration layer. The MEMS structure manufactured by the method improves the displacement and deformation of the piezoelectric composite vibration layer under the action of sound pressure, reduces the residual stress and further improves the sensitivity of the MEMS structure.

Description

Preparation method of MEMS structure
Technical Field
The present application relates to the field of semiconductor technology, and in particular, to a method for fabricating a structure of a MEMS (micro electro Mechanical Systems, which is abbreviated as micro electro Mechanical Systems).
Background
MEMS microphones (microphones) mainly include both capacitive type and piezoelectric type. The MEMS piezoelectric microphone is prepared by utilizing a micro-electro-mechanical system technology and a piezoelectric film technology, and has small size, small volume and good consistency due to the adoption of semiconductor planar technology, bulk silicon processing technology and other technologies. Meanwhile, compared with a capacitor microphone, the MEMS piezoelectric microphone also has the advantages of no bias voltage, large working temperature range, dust prevention, water prevention and the like, but the sensitivity is low, so that the development of the MEMS piezoelectric microphone is restricted. Among them, the large residual stress of the diaphragm is an important cause of low sensitivity thereof.
Aiming at the problems of reducing the residual stress of the piezoelectric MEMS structure and improving the deformation of the vibrating membrane in the related technology, no effective solution is provided at present.
Disclosure of Invention
Aiming at the problem of large residual stress in the related technology, the application provides a preparation method of an MEMS structure, which can effectively reduce the residual stress.
The technical scheme of the application is realized as follows:
according to an aspect of the present application, there is provided a method of fabricating a MEMS (micro electro mechanical system) structure, comprising:
etching a plurality of parallel second grooves in a peripheral area on the front surface of a substrate, and depositing and forming a piezoelectric composite vibration layer on the substrate, wherein the piezoelectric composite vibration layer formed on the bottom and the side wall of each second groove forms a first corrugated part;
depositing a mass block in the middle area of the piezoelectric composite vibration layer;
etching and forming a first groove on the exposed substrate outside the piezoelectric composite vibration layer;
etching the back surface of the substrate to form a cavity, wherein the first groove is adjacently arranged at the periphery of the cavity, and the piezoelectric composite vibration layer is formed right above the cavity, wherein the substrate at the part between the first groove and the cavity supports the piezoelectric composite vibration layer.
Wherein the method of forming the piezoelectric composite vibration layer includes:
depositing a support material on the substrate to form a vibrating support layer;
depositing a first electrode material on the vibration support layer, patterning the first electrode material to form a first electrode layer, and exposing a portion of the vibration support layer;
depositing a piezoelectric material over the first electrode layer and patterning the piezoelectric material to form a first piezoelectric layer;
depositing a second electrode material over the first piezoelectric layer, and patterning the second electrode material to form a second electrode layer.
Wherein the method of forming the mass comprises:
in the steps of patterning the first electrode material to form a first electrode layer, patterning the piezoelectric material to form a first piezoelectric layer, and patterning the second electrode material to form a second electrode layer, forming an opening continuously extending from an upper surface of the second electrode layer to a lower surface of the first electrode layer;
depositing the mass over the vibrating support layer within the opening.
Wherein the vibration support layer within the opening is etched to form a plurality of through holes through the vibration support layer, wherein the plurality of through holes are adjacent to edges of the opening and are distributed in a circle.
Wherein, before depositing a support material on the substrate to form the vibration support layer, a fourth groove is opened on the substrate in the area of the opening, and then the vibration support layer is conformally deposited, obtaining a second corrugated portion of the vibration support layer in the fourth groove, wherein the second corrugated portion is adjacent to the edge of the opening and is circular when viewed from a top view.
Wherein the method of forming the mass comprises:
depositing the proof mass over the second electrode layer.
Wherein etching forms a plurality of through holes that continuously penetrate through the vibration support layer, the first electrode layer, the first piezoelectric layer, and the second electrode layer, the plurality of through holes being adjacent to an edge of the proof mass and being distributed in a circle.
Wherein, before the step of depositing a support material on the substrate to form a vibration support layer, a fourth groove is opened on the substrate in an edge area of the proof mass, and then the vibration support layer, the first electrode layer, the first piezoelectric layer and the second electrode layer are conformally deposited, and a second corrugation part obtained in the fourth groove has the vibration support layer, the first electrode layer, the first piezoelectric layer and the second electrode layer protruding toward the substrate, wherein the second corrugation part is adjacent to the edge of the proof mass and is circular when viewed from a top view.
Wherein the first electrode layer, the first piezoelectric layer, and the second electrode layer protruding toward the substrate within the fourth groove are removed so that the second corrugated portion has only the vibration support layer remaining protruding toward the substrate.
Wherein the first corrugated portion formed on the bottom and the side wall of the second groove has the vibration support layer, the first electrode layer, the first piezoelectric layer, and the second electrode layer.
Wherein the first electrode layer, the first piezoelectric layer, and the second electrode layer formed on the bottom and the side walls of the second groove are removed, and the first corrugated portion has only the vibration support layer remaining on the bottom and the side walls of the second groove.
Wherein a central plane of one of the second grooves passes through a central point of the piezoelectric composite vibration layer and divides the piezoelectric composite vibration layer into two regions.
Wherein the plurality of parallel second grooves are arranged at equal intervals.
Wherein the method of forming the piezoelectric composite vibration layer further comprises:
etching the substrate to form a plurality of parallel third grooves, wherein the central plane of one third groove passes through the central point of the piezoelectric composite vibration layer, and the second groove and the third groove divide the piezoelectric composite vibration layer into four regions;
and depositing and forming the piezoelectric composite vibration layer on the substrate with the second groove and the third groove.
Wherein the method of forming the first groove comprises:
etching the exposed vibration support layer to form the first groove extending into the substrate.
The method for manufacturing the MEMS structure further comprises the steps of etching the first electrode layer and the second electrode layer respectively to form a fifth groove, separating the first electrode layer and the second electrode layer into at least two partitions by the fifth groove, forming electrode layer pairs by the partitions of the first electrode layer and the second electrode layer which correspond to each other, and then sequentially connecting the electrode pairs in series.
The vibration supporting layer comprises a single-layer or multi-layer composite membrane structure consisting of silicon nitride, silicon oxide, monocrystalline silicon and polycrystalline silicon; alternatively, the first and second electrodes may be,
the vibration support layer comprises a piezoelectric material layer and electrode material layers positioned above and below the piezoelectric material layer, wherein the piezoelectric material layer comprises one or more layers of zinc oxide, aluminum nitride, an organic piezoelectric film, lead zirconate titanate (PZT) or perovskite type piezoelectric film.
Wherein the density of the mass block is greater than that of silicon nitride.
In the MEMS structure manufactured by the method, the piezoelectric composite vibration layer is formed right above the cavity and is positioned in the middle of the first groove, so that part of the substrate material positioned between the first groove and the cavity supports the piezoelectric composite vibration layer, and the piezoelectric composite vibration layer is converted from a solid support state to a similar simple support state, therefore, the displacement and the deformation of the piezoelectric composite vibration layer under the action of sound pressure are improved, the residual stress is reduced, and the sensitivity of the MEMS structure is improved. Moreover, the mass block is beneficial to reducing the resonant frequency of the piezoelectric composite vibration layer and increasing the sensitivity of the MEMS structure.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
Various aspects of the present application may be better understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale and are used for illustration purposes only. In fact, the dimensions of the various elements may be arbitrarily increased or decreased for clarity of discussion.
FIG. 1 illustrates a perspective view of a MEMS structure, in accordance with some embodiments;
FIG. 2 illustrates a cross-sectional perspective view of a MEMS structure according to some embodiments;
FIG. 3 illustrates a perspective view of a substrate according to other embodiments;
FIGS. 4-15 illustrate cross-sectional views of intermediate stages of fabricating a MEMS structure, in accordance with some embodiments, wherein FIGS. 4-8, 10-11, and 13-15 are cross-sectional views taken along line A-A of FIG. 3, and FIG. 9 is a cross-sectional view taken along line B-B of FIG. 3; fig. 12 is an enlarged schematic view of portion C of fig. 11.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments that can be derived from the embodiments given herein by a person of ordinary skill in the art are intended to be within the scope of the present disclosure.
The following disclosure provides many different embodiments, or examples, for implementing different features of the application. Specific examples of components and arrangements are described below to simplify the present application. These are, of course, merely examples and are not intended to be limiting. For example, the dimensions of the elements are not limited to the disclosed ranges or values, but may depend on the process conditions and/or desired properties of the device. Further, in the following description, forming a first feature over or on a second feature may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. Various components may be arbitrarily drawn in different sizes for simplicity and clarity.
Furthermore, for ease of description, spatially relative terms such as "below", "lower", "above", "upper", and the like may be used herein to describe one element or component's relationship to another (or other) element or component as illustrated in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. Additionally, the term "made of can mean" including "or" consisting of.
According to the embodiment of the application, the MEMS structure is provided, so that the low-frequency sound leakage can be reduced and the working and preparation stability of the microphone can be improved while the residual stress and the strain of the piezoelectric composite vibration layer 20 are reduced.
Referring to fig. 1 and 2, a MEMS structure according to one embodiment of the present application is shown. The MEMS structure will be described in detail below. The MEMS structure includes a substrate 10, a piezoelectric composite vibration layer 20, and a mass 30.
The substrate 10 has a cavity 11 and a first groove 12 disposed adjacently, the first groove 12 being formed at the periphery of the cavity 11. The substrate 10 comprises silicon or any suitable silicon-based compound or derivative (e.g., silicon wafer, SOI, SiO)2Polysilicon on Si).
The piezoelectric composite vibration layer 20 is formed directly above the cavity 11 and in the middle of the first groove 12. The substrate 10 at a portion between the first groove 12 and the cavity 11 supports the piezoelectric composite vibration layer 20. And has a first corrugated portion 25 in the peripheral region of the piezoelectric composite vibration layer 20.
Since the relative thickness of the piezoelectric composite vibration layer 20 is small, it is difficult to distinguish the respective layers in the piezoelectric composite vibration layer 20 in fig. 1 and 2. The structure of the piezoelectric composite vibration layer 20 will be described here simply. In addition, the specific structure of the piezoelectric composite vibration layer 20 can also be referred to in conjunction with fig. 4 to 9. In some embodiments, the piezoelectric composite vibration layer 20 includes a vibration support layer 24 formed over the substrate 10, a first electrode layer 21 formed over the vibration support layer 24, a first piezoelectric layer 22 formed over the first electrode layer 21, and a second electrode layer 23 formed over the first piezoelectric layer 22. The first piezoelectric layer 22 may convert the applied pressure into a voltage, and the first electrode layer 21 and the second electrode layer 23 may transmit the generated voltage to other integrated circuit devices.
In some embodiments, the vibration support layer 24 comprises silicon nitride (Si)3N4) Silicon oxide, monocrystalline silicon, polycrystalline silicon, or other suitable support material.
In some embodiments, the vibration support layer 24 may include a layer of piezoelectric material and layers of electrode material on top of and below the layer of piezoelectric material. Wherein the piezoelectric material layer comprises one or more layers of zinc oxide, aluminum nitride, an organic piezoelectric film, lead zirconate titanate (PZT), a perovskite-type piezoelectric film, or other suitable materials. In this case, the vibration support layer 24 functions as both support and piezoelectric.
In some embodiments, the first piezoelectric layer 22 comprises zinc oxide, aluminum nitride, an organic piezoelectric film, lead zirconate titanate (PZT), a perovskite-type piezoelectric film, or other suitable material. The first electrode layer 21 and the second electrode layer 23 include aluminum, gold, platinum, molybdenum, titanium, chromium, and a composite film composed of them or other suitable materials.
The mass 30 is formed in the middle region of the piezoelectric composite vibration layer 20, and helps to lower the resonant frequency of the piezoelectric composite vibration layer 20 and increase the sensitivity of the MEMS structure. The mass 30 has a density greater than that of silicon nitride. Specifically, the mass 30 has a density greater than 3.2kg/dm3. Preferably, the mass 30 has a density greater than 4.5kg/dm3. The material of the mass 30 may include tungsten, gold, silver, and the like.
In the MEMS structure of the above embodiment, the piezoelectric composite vibration layer 20 is formed directly above the cavity 11 and located in the middle of the first groove 12, so that a part of the substrate material located between the first groove 12 and the cavity 11 supports the piezoelectric composite vibration layer 20, and further the piezoelectric composite vibration layer 20 is changed from a clamped state to a quasi-simply-supported state, and therefore, the residual stress of the piezoelectric composite vibration layer 20 is reduced, the displacement and deformation of the piezoelectric composite vibration layer 20 under the action of sound pressure are improved, and the sensitivity of the MEMS structure is further improved. Furthermore, the mass 30 helps to lower the resonant frequency of the piezoelectric composite vibration layer 20, increasing the sensitivity of the MEMS structure.
A method of fabricating the MEMS structure will be described below. The MEMS structure provided by the present application can be more easily understood by the manufacturing method of the MEMS structure.
The application provides a method of fabricating a MEMS (micro-electro-mechanical system) structure, comprising:
referring to fig. 3 and 4, wherein fig. 4 is a sectional view taken along line a-a of fig. 3. Step S101: a plurality of parallel second grooves 13 and a plurality of parallel third grooves 14 are etched in the peripheral region on the front surface of the substrate 10. The center plane of one of the second grooves 13 passes through the center point of the piezoelectric composite vibration layer 20, and divides the piezoelectric composite vibration layer 20 into two regions. In some embodiments, the plurality of parallel second grooves 13 are arranged at equal intervals. In some embodiments, a central plane of one of the third grooves 14 passes through a central point of the piezoelectric composite vibration layer 20, and the second groove 13 and the third groove 14 divide the piezoelectric composite vibration layer 20 into four regions.
Referring to fig. 5 to 8 in sequence, step S102: a piezoelectric composite vibration layer 20 is deposited on the substrate 10 having the second and third grooves 13 and 14. The method of forming the piezoelectric composite vibration layer 20 specifically includes: depositing a support material on the substrate 10 having the second and third grooves 13 and 14 to form a vibration support layer 24; depositing a first electrode material on the vibration support layer 24, and patterning the first electrode material to form the first electrode layer 21, and exposing a portion of the vibration support layer 24; depositing a piezoelectric material over the first electrode layer 21 and patterning the piezoelectric material to form a first piezoelectric layer 22; a second electrode material is deposited over the first piezoelectric layer 22 and patterned to form a second electrode layer 23. The materials of the substrate 10, the vibration support layer 24, the first electrode layer 21, the first piezoelectric layer 22, and the second electrode layer 23 have been described above and will not be described again.
Referring to fig. 9, fig. 9 is a sectional view of the piezoelectric composite vibration layer 10 formed along the line B-B in fig. 3. In some embodiments, the vibration support layer 24, the first electrode layer 21, the first piezoelectric layer 22, and the second electrode layer 23 formed on the bottom and the side walls of the second groove 13 and the third groove 14 constitute the first corrugated portion 25. The corrugated shape can be clearly seen in fig. 9.
In some embodiments, the first electrode layer 21, the first piezoelectric layer 22, and the second electrode layer 23 formed on the bottom and the side walls of the second groove 13 and the third groove 14 may be removed in a subsequent step process, so that the vibration support layer 24 remaining on the bottom and the side walls of the second groove 13 and the third groove 14 constitutes the first corrugated portion 25. In this case, a plurality of mutually independent sector-shaped regions are obtained, and each of the independent sector-shaped regions constitutes a piezoelectric thin film transducer of a cantilever-like structure.
Moreover, the first corrugated portion 25 can release the residual stress existing in the piezoelectric composite vibration layer 20 during deposition, while combining the cantilever-like structure, so that the "taut" piezoelectric composite vibration layer 20 becomes "soft". Thus, each sector of the piezoelectric composite vibration layer 20 obtains a large displacement and strain under the same sound pressure.
Referring to fig. 10, step S103: a mass 30 is deposited in the middle region of the piezoelectric composite vibration layer 20.
In some embodiments, an opening 26 may be provided in the piezoelectric composite vibration layer 20, with a mass 30 formed above the vibration support layer 24 within the opening 26. Specifically, the method of forming the mass 30 over the vibrating support layer 24 within the opening 26 includes: in the steps of patterning the first electrode material to form the first electrode layer 21, patterning the piezoelectric material to form the first piezoelectric layer 22, and patterning the second electrode material to form the second electrode layer 23, the opening 26 continuously extending from the upper surface of the second electrode layer 23 to the lower surface of the first electrode layer 21 is formed.
A mass 30 is then deposited over the vibrating support layer 24 within the opening 26. The mass 30 helps to lower the resonant frequency of the piezoelectric composite vibration layer 20 and increase the sensitivity of the MEMS structure.
Referring to fig. 11 and 12, fig. 12 is an enlarged schematic view of a portion C of fig. 11. To "soften" the vibration support layer 24 within the openings 26, the vibration support layer 24 within the openings 26 may be etched to form a plurality of through holes 27 through the vibration support layer 24. Wherein the plurality of through holes 27 are adjacent to the edge of the opening 26 and are distributed in a circle. As an alternative to the embodiment with a plurality of through holes 27, the vibration support layer 24 in the opening 26 has a second corrugated portion (not shown in the figure) protruding towards the substrate 10. Wherein the second corrugated portion is adjacent to the edge of the opening 26 and is rounded as seen in a top view. The method of forming the second corrugated portion may include: a circumferential fourth groove (not shown) is formed in the substrate 10 in the area of the opening 26 before the vibration support layer 24 is deposited, and the vibration support layer 24 is then conformally deposited. Thus, the portion of the vibration support layer 24 formed in the fourth groove is referred to as a second corrugated portion.
By forming the plurality of through holes 27 or the second corrugation segment, the stress of the vibration support layer 24 adjacent to the edge of the opening 26 is relieved and the "tightened" vibration support layer 24 is made "soft". Under the same sound pressure, the "softened" vibrating support layer 24 obtains larger displacement and strain, thereby improving the sensitivity of the MEMS structure.
In other embodiments, the proof mass 30 may be deposited directly over the second electrode layer 23. In this case, a plurality of through holes 27 continuously penetrating the vibration support layer 24, the first electrode layer 21, the first piezoelectric layer 22, and the second electrode layer 23 may be etched, the plurality of through holes 27 being adjacent to the edge of the mass 30 and distributed in a circle. As an alternative to the plurality of through holes 27, a circumferential fourth groove (not shown in the figure) may be formed in the substrate 10 in the edge area of the proof mass 30 before the step of depositing the support material on the substrate 10 to form the vibration support layer 24, followed by conformally depositing the vibration support layer 24, the first electrode layer 21, the first piezoelectric layer 22 and the second electrode 23 layer. The second corrugated portion (not shown in the figure) in the fourth groove is obtained with the vibration support layer 24, the first electrode layer 21, the first piezoelectric layer 22 and the second electrode layer 23 protruding towards the substrate 10. Wherein the second corrugation is adjacent to the edge of the mass 30 and is rounded as seen from the top view. Alternatively, the first electrode layer 21, the first piezoelectric layer 22, and the second electrode layer 23 protruding toward the substrate 10 in the fourth groove may be removed so that the second corrugated portion has only the vibration support layer 24 remaining protruding toward the substrate 10.
Referring to fig. 13, step S104: outside the first electrode layer 21, the first piezoelectric layer 22 and the second electrode layer 23, a first groove 12 is etched in the exposed substrate 10. In some embodiments, the first groove 12 extending into the substrate 10 may be etched on the exposed vibration support layer 24, so that the piezoelectric composite vibration layer 20 is converted from a solid-supported state to a simple-supported state, thereby improving the displacement and deformation of the piezoelectric composite vibration layer 20 under the action of the sound pressure, and further improving the sensitivity of the MEMS structure.
Referring to fig. 14 and 15, step S105: the back surface of the substrate 10 is etched to form a cavity 11, and a first groove 12 is adjacently disposed at the periphery of the cavity 11. And, the vibration support layer 24, the first electrode layer 21, the first piezoelectric layer 22, and the second electrode layer 23 are formed right above the cavity 11. Wherein the substrate 10 at a portion between the first groove 12 and the cavity 11 supports the piezoelectric composite vibration layer 20. Specifically, the method comprises the following steps: the cavity 11 is formed by depositing an insulating material 40 and a photoresist on the back surface of the substrate 10 in sequence through a standard photolithography process, patterning the photoresist to form a mask layer, and etching the exposed insulating material 40 and the substrate 10. The insulating material 40 on the back side of the substrate 10 is then removed.
Further, the method for manufacturing the MEMS device further includes etching the first electrode layer 21 and the second electrode layer 23 to form a fifth groove (not shown in the figure), where the fifth groove separates the first electrode layer 21 and the second electrode layer 23 into at least two partitions, and the partitions of the first electrode layer 21 and the second electrode layer 23 corresponding to each other form an electrode pair, and then sequentially connect the electrode pairs in series, so that the piezoelectric thin film transducers of the cantilever structures are electrically connected in series, thereby further improving the sensitivity of the MEMS structure.
In summary, according to the above technical solution of the present application, by using the method for manufacturing the MEMS structure, the residual stress of the piezoelectric composite vibration layer 20 is reduced, and the deformation of the piezoelectric composite vibration layer 20 under the action of the sound pressure is improved, so that the sensitivity of the MEMS structure is improved.
The above description is only exemplary of the present application and should not be taken as limiting the present application, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims (20)

1. A method of fabricating a MEMS structure, comprising:
etching a plurality of parallel radial second grooves in the peripheral area on the front surface of a substrate, and depositing and forming a piezoelectric composite vibration layer on the substrate, wherein the piezoelectric composite vibration layer formed on the bottom and the side wall of each second groove forms a first corrugated part;
depositing a mass block in the middle area of the piezoelectric composite vibration layer;
etching the back surface of the substrate to form a cavity, wherein the piezoelectric composite vibration layer is formed right above the cavity.
2. The method of fabricating a MEMS structure of claim 1, wherein the method of forming the piezoelectric composite vibration layer comprises:
depositing a support material on the substrate to form a vibrating support layer;
depositing a first electrode material on the vibration support layer, patterning the first electrode material to form a first electrode layer, and exposing a portion of the vibration support layer;
depositing a piezoelectric material over the first electrode layer and patterning the piezoelectric material to form a first piezoelectric layer;
depositing a second electrode material over the first piezoelectric layer, and patterning the second electrode material to form a second electrode layer.
3. The method of fabricating a MEMS structure of claim 2, wherein the method of forming the proof mass comprises:
in the steps of patterning the first electrode material to form a first electrode layer, patterning the piezoelectric material to form a first piezoelectric layer, and patterning the second electrode material to form a second electrode layer, forming an opening continuously extending from an upper surface of the second electrode layer to a lower surface of the first electrode layer;
depositing the mass over the vibrating support layer within the opening.
4. The method of fabricating a MEMS structure of claim 3, wherein the vibrating support layer within the opening is etched to form a plurality of vias through the vibrating support layer, wherein the plurality of vias are adjacent to edges of the opening and are distributed in a circle.
5. A method of manufacturing a MEMS structure according to claim 3, wherein a fourth recess is made in the substrate in the area of the opening before depositing a support material on the substrate to form the vibration support layer, and wherein the vibration support layer is then conformally deposited, resulting in a second corrugated portion of the vibration support layer in the fourth recess, wherein the second corrugated portion is adjacent to an edge of the opening and is rounded when viewed from a top view.
6. The method of fabricating a MEMS structure of claim 2, wherein the method of forming the proof mass comprises:
depositing the proof mass over the second electrode layer.
7. The method of fabricating a MEMS structure of claim 6, wherein etching forms a plurality of through holes continuously through the vibration support layer, the first electrode layer, the first piezoelectric layer, and the second electrode layer, the plurality of through holes being adjacent to an edge of the proof mass and being distributed in a circle.
8. A method of manufacturing a MEMS structure according to claim 6, characterized in that before the step of depositing a support material on the substrate to form a vibration support layer, a fourth recess is opened in the substrate in the edge area of the proof mass, after which the vibration support layer, the first electrode layer, the first piezoelectric layer and the second electrode layer are conformally deposited, and a second corrugation in the fourth recess is obtained having the vibration support layer, the first electrode layer, the first piezoelectric layer and the second electrode layer protruding towards the substrate, wherein the second corrugation is adjacent to the edge of the proof mass and is circular as seen from a top view.
9. The method of manufacturing a MEMS structure of claim 8, wherein the first electrode layer, the first piezoelectric layer, and the second electrode layer protruding toward the substrate within the fourth groove are removed so that the second corrugated portion has only the vibration support layer remaining protruding toward the substrate.
10. The method of manufacturing a MEMS structure according to claim 2, wherein the first corrugated portion formed on the bottom and the side wall of the second groove has the vibration support layer, the first electrode layer, the first piezoelectric layer, and the second electrode layer.
11. The method of manufacturing a MEMS structure according to claim 2, wherein the first electrode layer, the first piezoelectric layer, and the second electrode layer formed on the bottom and the side walls of the second groove are removed, and the first corrugated portion has only the vibration support layer remaining on the bottom and the side walls of the second groove.
12. The method of manufacturing a MEMS structure according to claim 1, wherein a central plane of one of the second grooves passes through a central point of the piezoelectric composite vibration layer and divides the piezoelectric composite vibration layer into two regions.
13. A method of fabricating a MEMS structure according to claim 1 wherein a plurality of parallel second grooves are provided at equal intervals.
14. The method of fabricating a MEMS structure of claim 1, wherein the method of forming the piezoelectric composite vibration layer further comprises:
etching the substrate to form a plurality of parallel third grooves, wherein the central plane of one third groove passes through the central point of the piezoelectric composite vibration layer, and the second groove and the third groove divide the piezoelectric composite vibration layer into four regions;
and depositing and forming the piezoelectric composite vibration layer on the substrate with the second groove and the third groove.
15. The method of fabricating a MEMS structure of claim 1,
and etching to form a first groove on the substrate outside the piezoelectric composite vibration layer, wherein the first groove is adjacently arranged at the periphery of the cavity, and the substrate positioned at the part between the first groove and the cavity supports the piezoelectric composite vibration layer.
16. The method of fabricating a MEMS structure of claim 15, wherein the method of forming the first recess comprises:
and etching the piezoelectric composite vibration layer to form the first groove extending into the substrate.
17. The method of manufacturing a MEMS structure according to claim 2, further comprising etching the first electrode layer and the second electrode layer to form a fifth groove, respectively, the fifth groove separating the first electrode layer and the second electrode layer into at least two partitions, the partitions of the first electrode layer and the second electrode layer corresponding to each other constituting an electrode layer pair, and then sequentially connecting a plurality of the electrode pairs in series.
18. The method of fabricating a MEMS structure of claim 2, wherein the vibrating support layer comprises a single or multi-layer composite membrane structure of silicon nitride, silicon oxide, single crystal silicon, polysilicon.
19. The method of fabricating a MEMS structure of claim 1, wherein the mass has a density greater than a density of silicon nitride.
20. The method of fabricating a MEMS structure of claim 1, wherein the vibration support layer comprises a piezoelectric material layer and electrode material layers on and under the piezoelectric material layer, wherein the piezoelectric material layer comprises one or more of zinc oxide, aluminum nitride, an organic piezoelectric film, lead zirconate titanate, or a perovskite-type piezoelectric film.
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