CN111884647B - Coupling isolation method for piezoelectric micromechanical acoustic transducer array - Google Patents
Coupling isolation method for piezoelectric micromechanical acoustic transducer array Download PDFInfo
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- CN111884647B CN111884647B CN202010809712.3A CN202010809712A CN111884647B CN 111884647 B CN111884647 B CN 111884647B CN 202010809712 A CN202010809712 A CN 202010809712A CN 111884647 B CN111884647 B CN 111884647B
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- 238000002955 isolation Methods 0.000 title claims abstract description 39
- 230000008878 coupling Effects 0.000 title claims abstract description 26
- 238000010168 coupling process Methods 0.000 title claims abstract description 26
- 238000005859 coupling reaction Methods 0.000 title claims abstract description 26
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 44
- 239000010703 silicon Substances 0.000 claims abstract description 44
- 230000026683 transduction Effects 0.000 claims abstract description 28
- 238000010361 transduction Methods 0.000 claims abstract description 28
- 238000005530 etching Methods 0.000 claims abstract description 21
- 238000000034 method Methods 0.000 claims abstract description 11
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 41
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 8
- 230000005284 excitation Effects 0.000 claims description 8
- 230000010355 oscillation Effects 0.000 claims description 6
- 230000000737 periodic effect Effects 0.000 claims description 5
- 235000012239 silicon dioxide Nutrition 0.000 claims description 4
- 239000000377 silicon dioxide Substances 0.000 claims description 4
- 238000010586 diagram Methods 0.000 description 12
- 238000003491 array Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 2
- 238000005457 optimization Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- 230000000644 propagated effect Effects 0.000 description 1
Classifications
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K19/00—Logic circuits, i.e. having at least two inputs acting on one output; Inverting circuits
- H03K19/02—Logic circuits, i.e. having at least two inputs acting on one output; Inverting circuits using specified components
- H03K19/14—Logic circuits, i.e. having at least two inputs acting on one output; Inverting circuits using specified components using opto-electronic devices, i.e. light-emitting and photoelectric devices electrically- or optically-coupled
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- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Computer Hardware Design (AREA)
- Computing Systems (AREA)
- General Engineering & Computer Science (AREA)
- Mathematical Physics (AREA)
- Transducers For Ultrasonic Waves (AREA)
Abstract
The invention discloses a piezoelectric micromechanical acoustic transducer array coupling isolation method. The piezoelectric micromechanical acoustic transducer array coupling isolation method comprises the following steps: etching a plurality of isolation grooves on the bottom silicon when the piezoelectric micromechanical acoustic transducer array is processed, so that the bottom silicon is divided into a plurality of transduction areas; at least one cavity is etched in each transduction region. The invention adopts the method of etching the isolation groove on the bottom silicon to block the propagation of the sound wave, thereby achieving the purpose of isolating the coupling between the transducers and improving the performance of the transducer array.
Description
Technical Field
The invention relates to the field of transducers, in particular to a piezoelectric micromechanical acoustic transducer array coupling isolation method.
Background
The piezoelectric micromechanical acoustic transducer is a transducer which can convert electric energy into acoustic energy by using the inverse piezoelectric effect of piezoelectric materials or convert acoustic energy into electric energy by using the piezoelectric effect, and can be used for a loudspeaker, a microphone or an ultrasonic sensor respectively corresponding to the transmitting and receiving states. In practical application, transducer arrays are often used, and the traditional piezoelectric micromechanical acoustic transducer arrays have coupling phenomenon, so that the performance of the array can be improved by improving the coupling of array elements in the array.
The structure of the piezoelectric micro-mechanical acoustic wave transducer is shown in fig. 1, which mainly comprises a top electrode, a piezoelectric film, a bottom electrode, top silicon, silicon dioxide and bottom silicon from top to bottom, wherein a cavity is formed by etching the bottom silicon, and after pulse excitation is applied to the top electrode and the bottom electrode of the transducer, the piezoelectric material deforms due to the inverse piezoelectric effect, so that periodic oscillation is formed, and acoustic waves are emitted.
In a common piezoelectric micromachined acoustic wave transducer array process, a plurality of back cavities are typically etched directly on the bottom silicon to form a transducer array, as shown in fig. 2.
After excitation of a certain transducer element or certain transducer elements in the array, the (part of the) transducer elements generate periodic oscillations emitting sound waves. However, since the propagation directions of the acoustic waves are all directions, the acoustic waves propagated transversely through the top silicon and the bottom silicon cause other transducers to oscillate and emit acoustic waves, i.e. the array elements are coupled with each other. FIG. 3 shows the coupled vibrations generated by exciting the left column and the right column. Further, the acoustic waves generated by the oscillation of other transducers may in turn interfere with the acoustic waves generated by the initial excitation of the array elements, resulting in poor array performance.
Therefore, a method for coupling and isolating a piezoelectric micromechanical acoustic transducer array is needed.
Disclosure of Invention
Based on the above, it is necessary to provide a coupling isolation method for a piezoelectric micromechanical acoustic transducer array, which uses a method of etching isolation grooves on a bottom silicon to block propagation of acoustic waves, thereby achieving the purpose of isolating coupling between transducers and improving performance of the transducer array.
In order to achieve the above object, the present invention provides the following solutions:
a piezoelectric micromechanical acoustic transducer array coupling isolation method comprises the following steps:
etching a plurality of isolation grooves on a bottom silicon when processing a piezoelectric micromechanical acoustic transducer array, so as to divide the bottom silicon into a plurality of transduction areas;
at least one cavity is etched in each of the transduction regions.
Optionally, a silicon dioxide layer, a top silicon layer and a plurality of piezoelectric structures are sequentially arranged on the bottom silicon from bottom to top; the position of the piezoelectric structure corresponds to the position of the cavity; the piezoelectric structure is sized to match the size of the cavity.
Optionally, the piezoelectric structure sequentially comprises a bottom electrode, a piezoelectric film and a top electrode from bottom to top, and after pulse excitation is applied to the bottom electrode and the top electrode, the piezoelectric film deforms, so that periodic oscillation is formed, and sound waves are emitted.
Optionally, the size of the cavity is determined by the set resonant frequency.
Optionally, the plurality of transduction regions on the bottom silicon are arranged in an array.
Optionally, the etched cavities in the transduction area are arranged in an array, and the sizes of the cavities are the same.
Optionally, etching a first cavity column and a second cavity column in the transduction region; the first cavity column includes a plurality of cavities of a first size; the second cavity column includes a plurality of cavities of a second size.
Compared with the prior art, the invention has the beneficial effects that:
the invention provides a coupling isolation method of a piezoelectric micro-mechanical acoustic transducer array, which comprises the steps of etching a plurality of isolation grooves on bottom silicon when the piezoelectric micro-mechanical acoustic transducer array is processed, so that the bottom silicon is divided into a plurality of transduction areas; at least one cavity is etched in each transduction region. According to the invention, the isolation groove is etched on the bottom silicon, and the air is arranged in the middle of the isolation groove, so that the sound waves generated by the excitation transducer can be blocked from being transmitted to other transducer units around, the influence of the excitation sound waves on other transducers is reduced, the problem of serious coupling among array elements is solved, and the performance of the transducer array is improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings that are needed in the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a block diagram of a conventional piezoelectric micromachined acoustic transducer;
FIG. 2 is a schematic diagram of a conventional bottom silicon etch of a piezoelectric micromachined acoustic transducer array;
FIG. 3 is a schematic diagram of coupled vibrations generated by two columns on the right side of a conventional piezoelectric micromachined acoustic transducer array when the left column is excited;
FIG. 4 is a schematic diagram of isolation trench etching of a bottom silicon of a common area array;
FIG. 5 is a schematic diagram of isolation trench etching of the bottom silicon of the transducer array;
FIG. 6 is a schematic diagram of isolation trench etching of bottom silicon of a multi-frequency linear array;
FIG. 7 is a schematic diagram showing vibration of two side columns when the middle column is excited after grooving optimization is performed on the linear array by adopting the coupling isolation method of the piezoelectric micromechanical acoustic transducer array.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention aims to provide a coupling isolation method for a piezoelectric micro-mechanical acoustic transducer array, which aims to solve the problem of serious coupling between different transducer units when the piezoelectric micro-mechanical acoustic transducer array is excited.
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.
The method is characterized in that the etching of the bottom silicon layer is optimized aiming at the coupling problem of the piezoelectric micromechanical acoustic transducer array, and the propagation of acoustic waves generated by exciting the transducer to the periphery is blocked by adding an isolation groove. The isolation trenches may be etched on top and bottom silicon, wherein the isolation trenches in the bottom silicon are more pronounced as the acoustic wave propagates mostly through the bottom silicon.
The piezoelectric micromechanical acoustic transducer array coupling isolation method provided by the embodiment comprises the following steps:
etching a plurality of isolation grooves on a bottom silicon when processing a piezoelectric micromechanical acoustic transducer array, so as to divide the bottom silicon into a plurality of transduction areas; at least one cavity is etched in each of the transduction regions.
As an alternative embodiment, a silicon dioxide layer, a top silicon layer and a plurality of piezoelectric structures are sequentially arranged on the bottom silicon from bottom to top; the position of the piezoelectric structure corresponds to the position of the cavity; the piezoelectric structure is sized to match the size of the cavity.
As an alternative implementation manner, the piezoelectric structure sequentially comprises a bottom electrode, a piezoelectric film and a top electrode from bottom to top, and when pulse excitation is applied to the bottom electrode and the top electrode, the piezoelectric film deforms, so that periodic oscillation is formed, and sound waves are emitted.
As an alternative embodiment, the size of the cavity is determined by the set resonance frequency.
As an alternative embodiment, a plurality of the transduction regions on the base silicon are arranged in an array.
As an alternative implementation manner, the etched cavities in the transduction area are arranged in an array, and the sizes of the cavities are the same. Fig. 4 and 5 are schematic diagrams of isolation trench etching of the bottom silicon of two different types of piezoelectric micromechanical acoustic transducer arrays, wherein fig. 4 is a schematic diagram of isolation trench etching of the bottom silicon of a common area array, and fig. 5 is a schematic diagram of isolation trench etching of the bottom silicon of a transducer array. In fig. 4, four isolation grooves 1 enclose a transduction area, a plurality of transduction areas are arranged in an array, and a cavity 2 is etched in the transduction area. In fig. 5, four isolation grooves 1 enclose a transduction area, a plurality of transduction areas are arranged in an array, a plurality of cavities arranged in an array are etched in each transduction area, and a plurality of cavities in the transduction areas form a cavity array 3.
As an alternative embodiment, the first cavity columns and the second cavity columns are etched in the transduction region; the first cavity column includes a plurality of cavities of a first size; the second cavity column includes a plurality of cavities of a second size. Fig. 6 is a schematic diagram of isolation trench etching of a bottom silicon of a multi-frequency linear array, including two types of transducers, a first cavity column formed by a plurality of cavities 4 of a first size on the left side, and a second cavity column formed by a plurality of cavities 5 of a second size on the right side.
FIG. 7 is a schematic diagram showing vibration of two side columns when the middle column is excited after grooving optimization is performed on the linear array by adopting the coupling isolation method of the piezoelectric micromechanical acoustic transducer array. Compared to fig. 3, it can be seen that there is a significant reduction in the amplitude of the coupling columns after slotting.
The invention optimizes the etching of the silicon layer of the piezoelectric micromechanical acoustic transducer array, solves the problem of coupling among array elements by a method of etching isolation grooves in the silicon layer, particularly bottom silicon, and optimizes the performance of the transducer array. The array can be various, and the isolation groove can be various, so the invention does not limit the types of the array and the isolation groove, and only the isolation groove is etched in the bottom silicon layer of the piezoelectric micro-mechanical acoustic transducer array.
In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other.
The principles and embodiments of the present invention have been described herein with reference to specific examples, the description of which is intended only to assist in understanding the methods of the present invention and the core ideas thereof; also, it is within the scope of the present invention to be modified by those of ordinary skill in the art in light of the present teachings. In view of the foregoing, this description should not be construed as limiting the invention.
Claims (5)
1. The piezoelectric micromechanical sound wave transducer array coupling isolation method is characterized by comprising the following steps of:
etching a plurality of isolation grooves on a bottom silicon when processing a piezoelectric micromechanical acoustic transducer array, so as to divide the bottom silicon into a plurality of transduction areas;
etching at least one cavity in each transduction region;
the four isolation grooves enclose a transduction area, the transduction areas are arrayed, a cavity or a plurality of cavities arrayed are etched in the transduction area, and the sizes of the cavities are the same;
or etching a first cavity column and a second cavity column in the transduction area; the first cavity column includes a plurality of cavities of a first size; the second cavity column includes a plurality of cavities of a second size.
2. The method for coupling and isolating the piezoelectric micromechanical acoustic transducer array according to claim 1, wherein a silicon dioxide layer, a top silicon layer and a plurality of piezoelectric structures are sequentially arranged on the bottom silicon from bottom to top; the position of the piezoelectric structure corresponds to the position of the cavity; the piezoelectric structure is sized to match the size of the cavity.
3. The method for coupling and isolating a piezoelectric micromechanical acoustic transducer array according to claim 2, wherein the piezoelectric structure comprises a bottom electrode, a piezoelectric film and a top electrode in sequence from bottom to top, and the piezoelectric film deforms when pulse excitation is applied to the bottom electrode and the top electrode, so that periodic oscillation is formed and acoustic waves are emitted.
4. A method of coupling and isolating a piezoelectric micromechanical acoustic transducer array according to claim 1, characterized in that the dimensions of the cavity are determined by the set resonant frequency.
5. The method of claim 1, wherein the plurality of transduction regions on the base silicon are arranged in an array.
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