CN117812509A - Directional MEMS speaker array and manufacturing method - Google Patents

Abstract

The invention discloses a directional MEMS speaker array and a manufacturing method, wherein the array comprises the following steps: the base plate comprises a plurality of columnar supporting feet, supporting beams and vibrating diaphragms which are arranged in an array manner; each columnar supporting foot is connected with the adjacent columnar supporting feet through supporting beams, a vibrating diaphragm is arranged between the three supporting beams of each adjacent three columnar supporting feet which are arranged in a triangle, the vibrating diaphragm is not contacted with the supporting beams, and the vibrating diaphragm is respectively connected with the adjacent three columnar supporting feet which are arranged in a triangle; each vibrating diaphragm surface is provided with a piezoelectric unit, and each piezoelectric unit comprises a first electrode, a piezoelectric film layer and a second electrode which are sequentially stacked, wherein the first electrode is arranged on one side of the piezoelectric film layer adjacent to the substrate. The directional MEMS loudspeaker array provided by the invention has small size, and the size and array arrangement can enable emitted ultrasonic waves to spontaneously interfere, so that the directional MEMS loudspeaker array has high directivity.

Description

Directional MEMS speaker array and manufacturing method

Technical Field

The embodiment of the invention relates to the technical field of directional loudspeakers, in particular to a directional MEMS loudspeaker array and a manufacturing method thereof.

Background

At present, a directional Micro-Electro-Mechanical System (MEMS) speaker system is mainly applied to outdoor scenes such as square dance and indoor scenes with larger space such as a bank hall exhibition hall and the like, but the requirements on miniaturized application scenes such as a bank ATM room, an automobile interior and the like are gradually improved.

However, conventional ultrasonic probes are typically large in size, and their packaging housing and pins determine that they require additional custom-made printed circuit boards (Printed Circuit Board, PCB) to be arrayed, and require manual assembly while being large in overall size, which is cumbersome to manufacture.

Disclosure of Invention

The embodiment of the invention provides a directional MEMS loudspeaker array and a manufacturing method, which can realize the same frequency as the traditional ultrasonic probe by adjusting the size and the thickness of a vibrating diaphragm of a single ultrasonic transmitting unit, and the size of the loudspeaker is small and the related array arrangement ensures that the transmitted ultrasonic waves can spontaneously interfere and have high directivity.

In a first aspect, embodiments of the present invention provide a directional MEMS speaker array comprising:

the substrate comprises a plurality of columnar supporting feet, supporting beams and vibrating diaphragms which are arranged in an array manner;

each columnar supporting foot is connected with the adjacent columnar supporting feet through supporting beams, a vibrating diaphragm is arranged among the three supporting beams of each adjacent three columnar supporting feet which are arranged in a triangle, the vibrating diaphragm is not contacted with the supporting beams, and the vibrating diaphragm is respectively connected with the adjacent three columnar supporting feet which are arranged in a triangle;

each vibrating diaphragm surface is provided with a piezoelectric unit, each piezoelectric unit comprises a first electrode, a piezoelectric film layer and a second electrode which are sequentially stacked, and the first electrode is arranged on one side, adjacent to the substrate, of the piezoelectric film layer.

Optionally, the surface of the support beam and the diaphragm adjacent to the piezoelectric unit is flush with the surface of the columnar support foot adjacent to the piezoelectric unit.

Optionally, the width of the gap between the support beam and the diaphragm ranges from greater than or equal to 25 microns to less than or equal to 225 microns.

Optionally, the thickness of the support beam is the same as the thickness of the diaphragm.

Optionally, the columnar support foot is cylindrical.

Optionally, the columnar support foot has a diameter of 2000 microns and a height in the range of greater than or equal to 350 microns and less than or equal to 725 microns;

the width of the support beam is greater than or equal to 50 microns and less than or equal to 450 microns.

Optionally, the distance between two adjacent diaphragms is 500 micrometers;

the thickness of the diaphragm was 50 microns.

Optionally, the connecting lines of the geometric centers of the adjacent three columnar supporting feet which are arranged in a triangle form are equilateral triangles.

Alternatively, the sides of the equilateral triangle are 4330 microns.

In a second aspect, an embodiment of the present invention provides a method for manufacturing a directional MEMS speaker array, including:

providing a substrate;

sequentially forming a first electrode material layer and a piezoelectric material layer on the first surface of the substrate;

patterning the first electrode material layer and the piezoelectric material layer to form a plurality of first electrodes and a plurality of piezoelectric thin film layers;

forming a second electrode on the surfaces of the first electrode and the piezoelectric film layer to form a plurality of piezoelectric units, wherein each piezoelectric unit comprises a first electrode, a piezoelectric film layer and a second electrode which are sequentially stacked;

etching the first surface of the substrate to remove part of the substrate at the preset position;

etching the second surface of the substrate to remove all the substrate at the preset position and thin the substrate in other areas to form a substrate comprising a plurality of columnar support feet, support beams and vibrating diaphragms which are arranged in an array manner; each adjacent columnar supporting foot is connected with each adjacent columnar supporting foot through a supporting beam, a vibrating diaphragm is arranged between every two adjacent three supporting beams of the three columnar supporting feet which are arranged in a triangular mode, the vibrating diaphragm is not contacted with the supporting beams, the vibrating diaphragms are respectively connected with the adjacent three columnar supporting feet which are arranged in a triangular mode, and each vibrating diaphragm surface is correspondingly provided with a piezoelectric unit.

According to the technical scheme provided by the embodiment of the invention, each columnar supporting foot is connected with the adjacent columnar supporting feet through the supporting beams, one vibrating diaphragm is arranged between the three supporting beams of each adjacent three columnar supporting feet which are arranged in a triangular mode, the vibrating diaphragm is not contacted with the supporting beams, and the vibrating diaphragm is respectively connected with the adjacent three columnar supporting feet which are arranged in a triangular mode. By the arrangement, the directional MEMS speaker array is closely arranged, and has a small size compared with the traditional ultrasonic probe array. Each vibrating diaphragm surface is provided with a piezoelectric unit, and each piezoelectric unit comprises a first electrode, a piezoelectric film layer and a second electrode which are sequentially stacked, wherein the first electrode is arranged on one side of the piezoelectric film layer adjacent to the substrate. The piezoelectric unit drives the vibrating diaphragm to vibrate by inputting alternating voltage into the first electrode and the second electrode, the directional MEMS loudspeaker array designed by the embodiment of the invention has small size, and the emitted ultrasonic waves interfere in the appointed direction by the columnar supporting feet, the supporting beams, the piezoelectric unit and the array arrangement of the vibrating diaphragm, so that the directional MEMS loudspeaker array has directivity. The MEMS speaker array provided by the embodiment of the invention can solve the defects of the traditional array, can achieve similar emission sound pressure level, has smaller size, and is manufactured once by adopting the MEMS technology without additional assembly and other operations. The same frequency as that of the traditional ultrasonic probe can be realized by adjusting the size of a single ultrasonic transmitting unit and the thickness of the vibrating diaphragm, so that the traditional transmitting array module can be replaced by a driving circuit of a traditional array system.

It should be understood that the description in this section is not intended to identify key or critical features of the embodiments of the invention or to delineate the scope of the invention. Other features of the present invention will become apparent from the description that follows.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic line drawing of a directional MEMS speaker array provided in accordance with an embodiment of the present invention;

fig. 2 is a perspective view of a directional MEMS speaker array provided by an embodiment of the present invention;

FIG. 3 is an enlarged view of a portion of a directional MEMS speaker array provided by an embodiment of the present invention;

FIG. 4 is a cross-sectional view of the directional MEMS speaker array of FIG. 3 taken along section line AA;

FIG. 5 is a dimensional view of a directional MEMS speaker array provided by an embodiment of the present invention;

fig. 6 is a schematic flow chart of a method for manufacturing a directional MEMS speaker array according to an embodiment of the present invention;

fig. 7 to 27 are schematic structural diagrams corresponding to steps of a method for manufacturing a directional MEMS speaker array according to an embodiment of the present invention.

Detailed Description

In order that those skilled in the art will better understand the present invention, a technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.

It should be noted that the terms "first," "second," and the like in the description and the claims of the present invention and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the invention described herein may be implemented in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

FIG. 1 is a schematic line drawing of a directional MEMS speaker array provided in accordance with an embodiment of the present invention; fig. 2 is a perspective view of a directional MEMS speaker array according to an embodiment of the present invention, fig. 3 is a partial enlarged view of a directional MEMS speaker array according to an embodiment of the present invention, and fig. 4 is a cross-sectional view of the directional MEMS speaker array of fig. 3 along a section line AA, see fig. 1-4, the directional MEMS speaker array comprising: the substrate 30, the substrate 30 includes a plurality of columnar support feet 10, a support beam 11 and a vibrating diaphragm 1 which are arranged in an array; each columnar supporting foot 10 is connected with the adjacent columnar supporting feet 10 through supporting beams 11, a vibrating diaphragm 1 is arranged between the three supporting beams 11 of each adjacent three columnar supporting feet 10 which are arranged in a triangle, the vibrating diaphragm 1 is not contacted with the supporting beams 11, and the vibrating diaphragm 1 is respectively connected with the adjacent three columnar supporting feet 10 which are arranged in a triangle; each vibrating diaphragm 1 is provided with a piezoelectric unit on the surface, the piezoelectric unit comprises a first electrode 2, a piezoelectric film layer 3 and a second electrode 6 which are sequentially stacked, and the first electrode 2 is arranged on one side, adjacent to the substrate, of the piezoelectric film layer 3.

Wherein one diaphragm 1 and one piezoelectric unit 31 are one transmitting unit for transmitting ultrasonic waves, and the substrate 30 may be a silicon substrate. The piezoelectric thin film layer 3 may be made of lead zirconate titanate material, and has a thickness of 2 μm. The first electrode 2 and the second electrode 6 may be copper electrodes, and the thickness of each of the first electrode and the second electrode is 0.2 μm.

Specifically, an alternating voltage is input in the vertical direction of the first electrode 6 and the second electrode 2, an electromagnetic field generated in the horizontal direction causes the piezoelectric film 3 to stretch and contract in the horizontal direction, thereby driving the diaphragm 1 to vibrate, the generated ultrasonic waves can interfere with each other, the frequency of the ultrasonic waves generated by each diaphragm 1 in a specified direction is the same due to the thickness of the diaphragm 1, the columnar support foot 10 and the size of the support beam 11, and the phases and frequencies of the ultrasonic waves generated in other directions are different, thereby causing the generated ultrasonic waves to be superimposed in the specified direction and to cancel out sound in other directions.

In the technical scheme provided by the embodiment of the invention, each columnar support foot 10 is connected with the adjacent columnar support feet 10 through the support beams 11, one vibrating diaphragm 1 is arranged between the three support beams 11 of each adjacent three columnar support feet 10 which are arranged in a triangular shape, the vibrating diaphragm 1 is not contacted with the support beams 11, and the vibrating diaphragm 1 is respectively connected with the adjacent three columnar support feet 10 which are arranged in a triangular shape. By the arrangement, the directional MEMS speaker array is closely arranged, and has a small size compared with the traditional ultrasonic probe array. Each diaphragm 1 is provided with a piezoelectric unit on its surface, and the piezoelectric unit 31 includes a first electrode 2, a piezoelectric thin film layer 3 and a second electrode 6 which are sequentially stacked, where the first electrode 2 is disposed on a side of the piezoelectric thin film layer 3 adjacent to the substrate. The piezoelectric unit 31 drives the vibrating diaphragm 1 to vibrate by inputting alternating voltages into the first electrode 2 and the second electrode 6, the directional MEMS speaker array designed by the embodiment of the invention has small size, and the emitted ultrasonic waves interfere in a specified direction by the columnar supporting feet 10, the supporting beam 11, the piezoelectric unit 31 and the array arrangement of the vibrating diaphragm 1, so that the directional MEMS speaker array has directivity. The MEMS speaker array provided by the embodiment of the invention can solve the defects of the traditional array, can achieve similar emission sound pressure level, has smaller size, and is manufactured once by adopting the MEMS technology without additional assembly and other operations. The same frequency as that of the traditional ultrasonic probe can be realized by adjusting the size of a single ultrasonic transmitting unit and the thickness of the vibrating diaphragm, so that the traditional transmitting array module can be replaced by a driving circuit of a traditional array system.

Referring to fig. 4, alternatively, the surface of the support beam 11 and the diaphragm 1 adjacent to the piezoelectric unit 31 is flush with the surface of the columnar support foot 10 adjacent to the piezoelectric unit 31 on the basis of the above embodiment.

In the embodiment of the present invention, the surfaces of the support beam 11 and the diaphragm 1 adjacent to the piezoelectric unit 31 are flush with the surfaces of the columnar support foot 10 adjacent to the piezoelectric unit 31 so that the piezoelectric unit 31 is more easily prepared on the upper surfaces of the support beam 11, the diaphragm 1, and the columnar support foot 10.

Referring to fig. 4, alternatively, the width of the gap between the support beam 11 and the diaphragm 1 may range from 25 micrometers or more to 225 micrometers or less, based on the above embodiment. In the embodiment of the invention, by setting the width range of the gap between the support beam 11 and the diaphragm 1 to be greater than or equal to 25 micrometers and less than or equal to 225 micrometers, not only can the support beam 11 and the diaphragm 1 be more easily prepared, but also the ultrasonic wave generated can have high directivity.

With continued reference to fig. 4, the support beam 11 may, optionally, have the same thickness as the diaphragm 1, as in the previous embodiment.

In the embodiment of the invention, the thickness of the supporting beam 11 is the same as that of the vibrating diaphragm 1, so that the supporting beam 11 and the vibrating diaphragm 1 can be formed by the same etching process, and the process steps are reduced.

With continued reference to fig. 4, the column-shaped support foot 10 is optionally cylindrical in shape, based on the embodiments described above.

Specifically, the cylindrical columnar supporting feet 10 are consistent with the connection relation between each supporting beam 11 and the vibrating diaphragm 1, the supporting forces of each supporting beam 11 and the vibrating diaphragm 1 are consistent, and the phenomenon that the vibration of the vibrating diaphragm is affected by inconsistent supporting forces is avoided, so that the ultrasonic frequency emitted by part of emitting units is inconsistent.

Fig. 5 is a dimensional view of a directional MEMS speaker array provided by an embodiment of the present invention, referring to fig. 5, the diameter of the columnar support foot 10 is 2000 micrometers, and the height range is greater than or equal to 350 micrometers and less than or equal to 725 micrometers, as an alternative to the above embodiments. The width of the support beam 11 is 50 micrometers or more and 450 micrometers or less.

Where c is denoted as the diameter of the cylindrical support column foot 10. d is the height of the column support foot 10. e denotes the width of the support beam 11.

In the embodiment of the present invention, by setting the diameter c of the columnar stay 10 to 2000 microns, the height d ranges from greater than or equal to 350 microns to less than or equal to 725 microns. The width e of the support beam 11 is 50 micrometers or more and 450 micrometers or less, so that the generated ultrasonic waves can interfere in a specified direction, and the directivity is high.

With continued reference to fig. 5, in an alternative embodiment, the distance between two adjacent diaphragms is 500 microns; the thickness of the diaphragm was 50 microns.

Where b is denoted as the distance between two adjacent diaphragms. f is denoted as the thickness of the diaphragm. The thickness of the vibrating diaphragm and the thickness of the supporting beam are both 50 micrometers. By the arrangement, the vibrating diaphragm is easier to manufacture, and the adjustable range of the vibrating frequency of the vibrating diaphragm is larger.

With continued reference to fig. 5, in the above embodiment, alternatively, the line connecting the geometric centers of the adjacent three columnar support feet 10 arranged in a triangle is an equilateral triangle.

In the embodiment of the invention, the directional MEMS speaker array is arranged in a way that the connecting lines of the geometric centers of the adjacent three columnar supporting feet 10 which are arranged in a triangle form are equilateral triangles, so that each emission unit in the directional MEMS speaker array is closely arranged, the size of the MEMS speaker array is smaller, and meanwhile, the directional MEMS speaker array also has high directivity.

With continued reference to fig. 5, the side length of the equilateral triangle can be 4330 microns, as an option, based on the above described embodiments.

Where a is denoted as the side length of an equilateral triangle. In the embodiment of the invention, the ultrasonic wave generated by vibrating the vibrating diaphragm has the same frequency, amplitude and phase in the designated direction by setting the side length of the equilateral triangle to 4330, so that accurate directional sounding is realized, and the high directivity is realized.

Fig. 6 is a schematic flow chart of a method for manufacturing a directional MEMS speaker array according to an embodiment of the present invention. Fig. 7 to 27 are schematic structural diagrams corresponding to steps of a method for manufacturing a directional MEMS speaker array according to an embodiment of the present invention. Referring to fig. 6, the method for manufacturing the directional MEMS speaker array includes:

s110, providing a substrate.

Referring to fig. 7, a substrate 30 is provided, and the substrate 30 may be a silicon substrate.

And S120, sequentially forming a first electrode material layer and a piezoelectric material layer on the first surface of the substrate.

Specifically, referring to fig. 8, the first electrode material layer 2 is formed on the first surface of the substrate 30 using a magnetron radio frequency sputtering process, and the piezoelectric material layer 3 is formed on the side of the first electrode material layer 2 away from the first surface of the substrate 1 using a magnetron radio frequency sputtering process.

And S130, patterning the first electrode material layer and the piezoelectric material layer to form a plurality of first electrodes and a plurality of piezoelectric film layers.

Specifically, referring to fig. 9, a first photoresist layer 4 is formed on a side of the piezoelectric material layer 3 away from the first surface of the substrate 1 by using a spin coating process, referring to fig. 10 to 11, a first mask shown in fig. 11 is used, a first photoresist layer 4 is formed by using an exposure and development technique, referring to fig. 12, and then a first trench 20 and a second trench 21 are formed in the piezoelectric material layer 3 by using an etching process, wherein the first trench 20 and the second trench 21 correspond to a gap of the first mask. Referring to fig. 13, the first photoresist layer is removed, and the first electrode 2 and the piezoelectric film 3 are formed on the first surface of the substrate 30.

And S140, forming a second electrode on the surfaces of the first electrode and the piezoelectric film layer to form a plurality of piezoelectric units, wherein each piezoelectric unit comprises the first electrode, the piezoelectric film layer and the second electrode which are sequentially stacked.

Specifically, referring to fig. 14, a second photoresist layer 5 is formed on the piezoelectric thin film layer through a spin coating process, referring to fig. 15 to 16, a second mask shown in fig. 16 is used, and a patterned second photoresist layer 5 is formed through photolithography and development techniques, referring to fig. 17, and a second electrode 6 is formed on the second photoresist layer 5 and the piezoelectric material layer 3 through a magnetron radio frequency sputtering process. Referring to fig. 18, the second photoresist layer 5 is removed, and the second electrode 6 is formed on the surfaces of the first electrode 2 and the piezoelectric thin film layer 3, thereby forming a plurality of piezoelectric units.

And S150, etching the first surface of the substrate to remove part of the substrate at the preset position.

Specifically, referring to fig. 19, a third photoresist layer 7 is formed on the surfaces of the first electrode 2, the piezoelectric thin film layer 3 and the second electrode 6 by a spin coating process, and referring to fig. 20 to 21, the patterned third photoresist layer 7 is formed by photolithography and development processes using a third mask shown in fig. 21. Referring to fig. 22, the first surface of the substrate 30 is etched by an etching process to remove a portion of the substrate 30 at a preset position.

And S160, etching the second surface of the substrate to remove all the substrate at the preset position and thin the substrate in other areas to form a substrate comprising a plurality of columnar support feet, support beams and vibrating diaphragms which are arranged in an array.

Each adjacent columnar supporting foot is connected with each adjacent columnar supporting foot through a supporting beam, a vibrating diaphragm is arranged between three supporting beams of each adjacent three columnar supporting feet which are arranged in a triangular mode, the vibrating diaphragm is not contacted with the supporting beams, the vibrating diaphragm is connected with the adjacent three columnar supporting feet which are arranged in a triangular mode, and each vibrating diaphragm surface is correspondingly provided with a piezoelectric unit.

Specifically, referring to fig. 23, the second surface of the substrate 30 is polished by a polishing process to enable the thickness of the substrate 1 to be polished from 750 micrometers to 350 micrometers, referring to fig. 24, a fourth photoresist layer 8 is formed on the second surface of the polished substrate 30 by a spin coating process, referring to fig. 25 to 26, the fourth photoresist layer 8 is patterned by a photolithography and development technique using the fourth mask shown in fig. 26, referring to fig. 27, the second surface of the substrate 30 is etched by an etching process to enable part of the substrate 30 in other areas to be thinned and all of the substrate 30 in a preset position to be removed, thereby forming a substrate including a plurality of array arrangement column-shaped support legs 10, support beams 11 and diaphragms 1. The backside cavity in fig. 26 corresponds to the portion of the second surface of the substrate 30 in fig. 27 that has been removed.

In the technical scheme provided by the embodiment of the invention, a substrate 30 is provided, a first electrode material layer 2 and a piezoelectric material layer 3 are sequentially formed on a first surface of the substrate 30, and the first electrode material layer 2 and the piezoelectric material layer 3 are patterned to form a plurality of first electrodes 2 and a plurality of piezoelectric film layers 3. Forming a second electrode 6 on the surfaces of the first electrode 2 and the piezoelectric film layer 3 to form a plurality of piezoelectric units, wherein each piezoelectric unit comprises the first electrode 2, the piezoelectric film layer 3 and the second electrode 6 which are sequentially stacked; etching the first surface of the substrate 30 to remove a part of the substrate 30 at a preset position; the second surface of the substrate 30 is etched to remove all the substrate 30 at the predetermined position, and a part of the substrate 30 at other regions is thinned to form a substrate 30 including a plurality of columnar support feet 10 arranged in an array, a support beam 11 and a diaphragm 1. The manufacturing method is simple, low in cost and capable of being integrated with various small micro systems by the MEMS technology based on silicon.

It should be appreciated that various forms of the flows shown above may be used to reorder, add, or delete steps. For example, the steps described in the present invention may be performed in parallel, sequentially, or in a different order, so long as the desired results of the technical solution of the present invention are achieved, and the present invention is not limited herein.

The above embodiments do not limit the scope of the present invention. It will be apparent to those skilled in the art that various modifications, combinations, sub-combinations and alternatives are possible, depending on design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of the present invention.

Claims (10)

1. A directional MEMS speaker array comprising:

the substrate comprises a plurality of columnar supporting feet, supporting beams and vibrating diaphragms which are arranged in an array manner;

each columnar supporting foot is connected with the adjacent columnar supporting feet through supporting beams, a vibrating diaphragm is arranged among the three supporting beams of each adjacent three columnar supporting feet which are arranged in a triangle, the vibrating diaphragm is not contacted with the supporting beams, and the vibrating diaphragm is respectively connected with the adjacent three columnar supporting feet which are arranged in a triangle;

each vibrating diaphragm surface is provided with a piezoelectric unit, each piezoelectric unit comprises a first electrode, a piezoelectric film layer and a second electrode which are sequentially stacked, and the first electrode is arranged on one side, adjacent to the substrate, of the piezoelectric film layer.

2. A directional MEMS speaker array as claimed in claim 1, wherein:

the surfaces of the support beam and the vibrating diaphragm adjacent to the piezoelectric unit are flush with the surfaces of the columnar support feet adjacent to the piezoelectric unit.

3. A directional MEMS speaker array as claimed in claim 1, wherein:

the width of the gap between the support beam and the vibrating diaphragm ranges from 25 micrometers or more to 225 micrometers or less.

4. A directional MEMS speaker array as claimed in claim 1, wherein:

the thickness of the supporting beam is the same as that of the vibrating diaphragm.

5. A directional MEMS speaker array as claimed in claim 1, wherein:

the columnar support foot is cylindrical.

6. A directional MEMS speaker array as claimed in claim 5, wherein:

the diameter of the columnar supporting foot is 2000 microns, and the height range is more than or equal to 350 microns and less than or equal to 725 microns;

the width of the support beam is greater than or equal to 50 microns and less than or equal to 450 microns.

7. A directional MEMS speaker array as claimed in claim 1, wherein:

the distance between two adjacent vibrating diaphragms is 500 microns;

the thickness of the diaphragm was 50 microns.

8. A directional MEMS speaker array as claimed in claim 1, wherein:

the connecting lines of the geometric centers of the three adjacent columnar supporting feet which are arranged in a triangle form are equilateral triangles.

9. A directional MEMS speaker array as claimed in claim 8, wherein:

the side length of the equilateral triangle is 4330 microns.

10. A method of fabricating a directional MEMS speaker array, comprising:

providing a substrate;

sequentially forming a first electrode material layer and a piezoelectric material layer on the first surface of the substrate;

patterning the first electrode material layer and the piezoelectric material layer to form a plurality of first electrodes and a plurality of piezoelectric thin film layers;

forming a second electrode on the surfaces of the first electrode and the piezoelectric film layer to form a plurality of piezoelectric units, wherein each piezoelectric unit comprises a first electrode, a piezoelectric film layer and a second electrode which are sequentially stacked;

etching the first surface of the substrate to remove part of the substrate at the preset position;

etching the second surface of the substrate to remove all the substrate at the preset position and thin the substrate in other areas to form a substrate comprising a plurality of columnar support feet, support beams and vibrating diaphragms which are arranged in an array manner; each adjacent columnar supporting foot is connected with each adjacent columnar supporting foot through a supporting beam, a vibrating diaphragm is arranged between every two adjacent three supporting beams of the three columnar supporting feet which are arranged in a triangular mode, the vibrating diaphragm is not contacted with the supporting beams, the vibrating diaphragms are respectively connected with the adjacent three columnar supporting feet which are arranged in a triangular mode, and each vibrating diaphragm surface is correspondingly provided with a piezoelectric unit.