阅读说明：本技术 Mems扬声器 (MEMS loudspeaker ) 是由 程诗阳 但强 周一苇 李杨 于 2021-07-07 设计创作，主要内容包括：本发明提供了一种MEMS扬声器,包括：衬底,衬底设有固定部和贯穿固定部的空腔；驱动器,驱动器覆盖空腔并固定于固定部,驱动器具有交替叠设的电极层和压电层,驱动器包括自衬底延伸的主体部以及与主体部连接的自由端,自由端相对于主体部具有更大的运动自由度,驱动器的表面设置有柔性膜,柔性膜沿驱动器的振动方向封闭空腔驱动器的表面设置有柔性膜,柔性膜连接多个自由端并沿驱动器的振动方向封闭空腔。该MEMS扬声器的自由端可以调整驱动器的整体刚度,从而提高了MEMS扬声器的最大声压输出。(The present invention provides a MEMS speaker, comprising: the substrate is provided with a fixed part and a cavity penetrating through the fixed part; the driver, the driver covers the cavity and is fixed in the fixed part, the driver has electrode layer and the piezoelectric layer of establishing in turn, the driver includes the main part that extends from the substrate and the free end of being connected with the main part, the free end has bigger degree of freedom of movement for the main part, the surface of driver is provided with flexible membrane, flexible membrane is provided with flexible membrane along the surface of the vibration direction closed cavity driver of driver, a plurality of free ends are connected to flexible membrane and the vibration direction closed cavity along the driver. The free end of the MEMS loudspeaker can adjust the integral rigidity of the driver, so that the maximum sound pressure output of the MEMS loudspeaker is improved.)

1. A MEMS speaker, comprising:

the substrate is provided with a fixed part and a cavity penetrating through the fixed part;

the driver covers the cavity and is fixed on the fixing part, the driver is provided with electrode layers and piezoelectric layers which are alternately stacked, and the electrode layers at least comprise a first electrode layer, a second electrode layer and a third electrode layer which are sequentially arranged at intervals; the piezoelectric layer at least comprises a first piezoelectric layer and a second piezoelectric layer, wherein the first piezoelectric layer is clamped between the first electrode layer and the second electrode layer, and the second piezoelectric layer is clamped between the second electrode layer and the third electrode layer.

2. The MEMS loudspeaker of claim 1, wherein the electrode layers can apply voltages of different directions and/or magnitudes to a plurality of the piezoelectric layers spaced between different ones of the electrode layers to drive the piezoelectric layers spaced between different ones of the electrode layers to obtain different degrees and/or directional displacements.

3. The MEMS loudspeaker of claim 1, wherein the driver has a slit or hole provided therethrough in the vibration direction.

4. The MEMS loudspeaker of claim 3, wherein the holes are arranged in a circular array, the line connecting the centers of the holes separating the free ends from the main body portion.

5. The MEMS loudspeaker of claim 3, wherein the slit comprises a plurality of slits, the plurality of slits being symmetrically distributed, the plurality of free ends comprising a plurality, the plurality of free ends being spaced apart by the slits.

6. The MEMS speaker as recited in claim 3, wherein the flexible membrane corresponds to a shape of the slit or hole.

7. The MEMS speaker as recited in any one of claims 1 to 6, wherein the flexible membrane is disposed on a side of the driver away from the cavity.

8. A method of making a MEMS speaker, comprising:

providing a substrate and cleaning;

depositing a first electrode layer on the surface of the substrate;

depositing and forming a first piezoelectric layer on one side of the first electrode layer far away from the substrate;

depositing a second electrode layer on one side of the first piezoelectric layer far away from the substrate;

depositing and forming a second piezoelectric layer on one side of the second electrode layer far away from the substrate;

depositing a third electrode layer on one side of the second piezoelectric layer far away from the substrate;

etching to form a cavity and a slit or a hole, and forming a flexible membrane.

9. The method of claim 8, wherein the flexible film is formed on the side of the third electrode layer away from the substrate by coating, and the cavity and the slit or hole are formed by etching.

10. The method of claim 8, wherein the flexible membrane is assembled after the cavity and the slit or hole are formed by etching.

[ technical field ] A method for producing a semiconductor device

The invention relates to the technical field of sound-electricity conversion, in particular to an MEMS (micro-electromechanical system) loudspeaker.

[ background of the invention ]

A speaker is one of main components of a mobile terminal such as a mobile phone, and mainly converts an electric signal into an audio signal.

The MEMS (Micro-Electro-Mechanical System), namely a Micro-electromechanical System loudspeaker, has the advantages of good consistency, low power consumption, small size, low price and the like compared with the traditional voice coil loudspeaker, the traditional MEMS loudspeaker adopts a double piezoelectric layer reverse driving mode to improve the energy conversion efficiency, but because the structure has no free end, the self-limiting effect can be generated during vibration. Furthermore, the structure contains two piezoelectric layers, which further constrains the end displacement and thus affects the maximum sound pressure output that can be achieved by the system.

Therefore, there is a need to provide a MEMS speaker that improves upon the above-mentioned problems.

[ summary of the invention ]

The invention aims to provide a MEMS loudspeaker which reduces self-limiting effect and improves maximum sound pressure output.

In order to achieve the above object, the present invention provides a MEMS speaker, comprising:

the substrate is provided with a fixed part and a cavity penetrating through the fixed part;

the driver covers the cavity and is fixed on the fixing part, the driver is provided with electrode layers and piezoelectric layers which are alternately stacked, and the electrode layers at least comprise a first electrode layer, a second electrode layer and a third electrode layer which are sequentially arranged at intervals; the piezoelectric layer at least comprises a first piezoelectric layer and a second piezoelectric layer, the first piezoelectric layer is arranged between the first electrode layer and the second electrode layer in a clamped mode, the second piezoelectric layer is arranged between the second electrode layer and the third electrode layer in a clamped mode, the driver comprises a main body portion extending from the substrate and a free end connected with the main body portion, the free end has larger movement freedom degree relative to the main body portion, a flexible membrane is arranged on the surface of the driver, and the flexible membrane seals the cavity along the vibration direction of the driver.

Preferably, the electrode layers can apply voltages of different directions and/or magnitudes to a plurality of the piezoelectric layers spaced between different electrode layers to drive the piezoelectric layers spaced between different electrode layers to obtain different degrees and/or directional displacements.

Preferably, the driver is provided with a slit or a hole penetrating along the vibration direction.

Preferably, the holes are arranged in a circular array, and a line connecting centers of the holes separates the free ends from the main body part.

Preferably, the slit includes a plurality of slits, the plurality of slits are symmetrically distributed, the plurality of free ends include a plurality of slits, and the plurality of free ends are spaced apart by the slits.

Preferably, the flexible membrane corresponds to the shape of the slit or hole.

Preferably, the flexible membrane is disposed on a side of the driver away from the cavity.

The invention also provides a method for preparing the MEMS loudspeaker, which comprises the following steps:

providing a substrate and cleaning;

depositing a first electrode layer on the surface of the substrate;

depositing and forming a first piezoelectric layer on one side of the first electrode layer far away from the substrate;

depositing a second electrode layer on one side of the first piezoelectric layer far away from the substrate;

depositing and forming a second piezoelectric layer on one side of the second electrode layer far away from the substrate;

depositing a third electrode layer on one side of the second piezoelectric layer far away from the substrate;

etching to form a cavity and a slit or a hole, and forming a flexible film;

preferably, the flexible film is formed on one side of the third electrode layer away from the substrate by coating, and the cavity and the slit or the hole are formed by etching.

Preferably, the flexible membrane is assembled after the cavity and the slit or hole are formed by etching.

The invention has the beneficial effects that: in the invention, the driver comprises the free end with more freedom of movement, so that the self-limiting effect generated by the driver during vibration is reduced, and the maximum sound pressure output of the MEMS loudspeaker is improved. Furthermore, the flexible film is arranged to seal the cavity, so that acoustic short circuit is avoided, the performance of the medium-high frequency is more prominent (harmonic distortion is effectively inhibited), and the displacement amplitude of the driver is improved to the maximum extent.

[ description of the drawings ]

Fig. 1 is a schematic perspective view of a MEMS speaker according to a first embodiment of the present invention;

fig. 2 is an exploded view of a MEMS speaker according to a first embodiment of the present invention;

FIG. 3 is a cross-sectional view A-A of FIG. 1;

FIG. 4 is an enlarged view of FIG. 3 at B;

fig. 5 is an exploded view of a MEMS speaker according to a second embodiment of the present invention;

FIGS. 6A-6I are schematic diagrams of steps of a method of making a MEMS speaker according to an embodiment of the invention;

FIGS. 7A-7B are schematic diagrams of a portion of steps in a method of fabricating a MEMS speaker according to another embodiment of the present invention;

[ detailed description ] embodiments

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

Referring to fig. 1-4, the present invention provides a MEMS speaker 100 including a substrate 1 and a driver 2 fixed to the substrate 1.

Specifically, the substrate 1 is provided with a fixing portion 11 and a cavity 10 penetrating through the fixing portion 11, and the driver 2 covers the cavity 10 and is fixed on the fixing portion 11; the driver 2 comprises an electrode layer 21 and a piezoelectric layer 22 which are alternately stacked, the electrode layer 21 at least comprises a first electrode layer 211, a second electrode layer 212 and a third electrode layer 213 which are sequentially arranged at intervals, and the first electrode layer 211 covers the cavity 10 and is fixed on the fixing part 11; the piezoelectric layer 22 at least includes a first piezoelectric layer 221 sandwiched between the first electrode layer 211 and the second electrode layer 212, and a second piezoelectric layer 222 sandwiched between the second electrode layer 212 and the third electrode layer 213, and the piezoelectric material used for the piezoelectric layer 22 includes, but is not limited to, lead zirconate titanate (PZT), aluminum nitride (AlN), zinc oxide (ZnO), and the like. The driver 2 completely covers the fixing portion 11.

In this embodiment, the electrode layer 21 includes a first electrode layer 211, a second electrode layer 212, and a third electrode layer 213 disposed at intervals in sequence, and the first electrode layer 211 covers the cavity 10 and is fixed on the fixing portion 11; the piezoelectric layer 22 includes a first piezoelectric layer 221 interposed between the first electrode layer 211 and the second electrode layer 212, and a second piezoelectric layer 222 interposed between the second electrode layer 212 and the third electrode layer 213.

The actuator 2 is provided with a slit 25 extending through the vibration direction, that is, the slit 25 extends through both the electrode layer 21 and the piezoelectric layer 22, and the slits 25 are symmetrically arranged, so that the actuator 2 is divided into a plurality of free ends 23 capable of moving independently, and the free ends 23 are spaced by the slits 25. The driving part further comprises a main body part 24 fixed on the substrate 1 and extending inwards, the main body part 24 is connected with the free end 23, the free end 23 has a larger freedom of movement relative to the main body part 24, the overall rigidity of the driver 2 is adjusted by arranging the free end 23 with the larger freedom of movement, the self-limiting effect generated by the driver 2 during vibration and sound production is reduced, and the maximum sound pressure output of the MEMS speaker 100 is improved.

Furthermore, a flexible membrane 26 is arranged on the surface of one side, away from the cavity 10, of the driver 2 of the MEMS speaker 100, and the flexible membrane 26 seals the cavity 10 along the vibration direction of the driver 2, so that the MEMS speaker 100 avoids the phenomenon of acoustic short circuit and improves the performance of the MEMS speaker at medium and high frequencies.

As shown in fig. 1 to 4, the flexible film 26 corresponds to the shape of the slit 25, and is configured such that the flexible film 24 can keep the minimum volume to close the cavity 10, thereby reducing the production cost of the product.

As shown in fig. 5, in the MEMS speaker according to the second embodiment of the present invention, the driver 2 is provided with a hole 25a, the driver further includes a main body portion 24a and a free end 23a, the free end 23a has a greater freedom of movement relative to the main body portion 24a, the holes 25a are arranged in a circular array, and a line connecting centers of the holes 25a separates the free end 23a from the main body portion 24 a. In the second embodiment of the present invention, a flexible film 26a is disposed on a side of the driver 2 away from the cavity, as shown in fig. 5, and the flexible film 26a conforms to the shape of the driver and closes the cavity, so that the integrated processing of the MEMS speaker is facilitated.

As shown in fig. 6A to 6I, a method for manufacturing a MEMS speaker according to the present invention includes providing a substrate 1 and cleaning; (FIG. 6A)

Depositing a first electrode layer 211 on the surface of the substrate 1; (FIG. 6B)

Depositing and forming a first piezoelectric layer 221 on the side, away from the substrate 1, of the first electrode layer 211; (FIG. 6C)

Depositing a second electrode layer 212 on the side of the first piezoelectric layer 221 away from the substrate 1; (FIG. 6D)

Depositing a second piezoelectric layer 222 on the side of the second electrode layer 212 far away from the substrate 1; (FIG. 6E)

Depositing a third electrode layer 213 on the side of the second piezoelectric layer 222 away from the substrate 1; (FIG. 6F)

Depositing and forming a flexible film 26 on the side, away from the substrate 1, of the third electrode layer 213; (FIG. 6G)

Etching the substrate 1 to form a cavity 10; (FIG. 6H)

Continuously etching to form a slit 25; (FIG. 6I)

The MEMS loudspeaker is prepared according to the steps, so that all preparation processes are consistent.

In other alternative embodiments, as shown in fig. 7A to 7B, after the third electrode layer is formed (shown in fig. 6F), the back cavity 10 and the slit 25 are formed by etching (shown in fig. 7A), and then the flexible film 26 is disposed through the assembling process; since the flexible membrane 26 is disposed on the MEMS speaker through an assembling process, the position thereof can be easily adjusted, for example, the flexible membrane 26 can be disposed on the side of the first electrode layer 211 close to the cavity 10.

It should be noted that the terms "first," "second," and the like in the description and claims of this application and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application described herein are, for example, capable of operation 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.

The above are only embodiments of the present invention, and it should be noted that, for those skilled in the art, modifications can be made without departing from the inventive concept of the present invention, but these are all within the scope of the present invention.