阅读说明：本技术 一种压电式麦克风及其制作方法 (Piezoelectric microphone and manufacturing method thereof ) 是由 石正雨 童贝 于 2020-11-30 设计创作，主要内容包括：本发明提供了一种压电式麦克风,包括具有背腔的基底,以及固定在所述基底上方的压电悬臂梁振膜；压电悬臂梁振膜至少包括第一子振膜和第二子振膜,每一子振膜一端与基底固定形成固定端,另一端悬置于背腔上方形成与固定端连接的活动端,活动端的宽度不小于固定端的宽度,压电式麦克风还包括弹性伸缩件,弹性伸缩件一端连接着第一子振膜的活动端,另一端连接着第二子振膜和/或基底上。本发明的悬臂梁活动端的宽度不小于固定端的宽度,在声压作用下将产生更大力矩,从而提高麦克风信噪比。(The invention provides a piezoelectric microphone, which comprises a substrate with a back cavity and a piezoelectric cantilever beam diaphragm fixed above the substrate; the piezoelectric type microphone also comprises an elastic expansion piece, one end of the elastic expansion piece is connected with the movable end of the first sub vibrating diaphragm, and the other end of the elastic expansion piece is connected with the second sub vibrating diaphragm and/or the substrate. The width of the movable end of the cantilever beam is not less than that of the fixed end, and larger moment is generated under the action of sound pressure, so that the signal-to-noise ratio of the microphone is improved.)

1. A piezoelectric microphone comprises a substrate with a back cavity and a piezoelectric cantilever beam diaphragm fixed above the substrate; piezoelectric cantilever beam vibrating diaphragm includes first sub-vibrating diaphragm and the sub-vibrating diaphragm of second at least, each sub-vibrating diaphragm one end with the fixed stiff end that forms of basement, other end suspension in back of the body chamber top forms the expansion end of being connected with the stiff end, its characterized in that, the width of expansion end is not less than the width of stiff end, piezoelectric microphone still includes elastic expansion spare, elastic expansion spare one end is being connected the expansion end of first sub-vibrating diaphragm, the other end is being connected on sub-vibrating diaphragm of second and/or the basement.

2. The piezoelectric microphone of claim 1, wherein:

the back cavity is square, connects first sub-vibrating diaphragm with the second sub-vibrating diaphragm the elasticity extensible member is located the axis of square, and with the stiff end of first sub-vibrating diaphragm with the second sub-vibrating diaphragm is parallel.

3. The piezoelectric microphone of claim 1, wherein:

the back cavity is octagonal, the elastic telescopic end connected with the first sub-diaphragm and the second sub-diaphragm is located on the axis of the octagonal, and the elastic telescopic end is parallel to the fixed end of the first sub-diaphragm and the fixed end of the second sub-diaphragm.

4. The piezoelectric microphone of claim 1, wherein:

the back cavity is hexagonal, connects first sub-vibrating diaphragm with the second sub-vibrating diaphragm the flexible end is located hexagonal axis, and with the stiff end of first sub-vibrating diaphragm with the second sub-vibrating diaphragm is parallel.

5. The piezoelectric microphone of claim 1, wherein:

the back of the body chamber is the cross, connects first sub-vibrating diaphragm with the sub-vibrating diaphragm of second the flexible end is located crisscross axis, and with first sub-vibrating diaphragm with the stiff end of the sub-vibrating diaphragm of second is parallel.

6. The piezoelectric microphone according to any one of claims 1 to 5, wherein: the elastic telescopic piece is of a flexible spring structure.

7. The piezoelectric microphone according to any one of claims 1 to 5, wherein: the elastic expansion piece is a hollow pattern on the piezoelectric cantilever diaphragm.

8. The piezoelectric microphone of claim 7, wherein: the hollow pattern comprises a square-shaped groove, a Chinese character 'Wan' shaped groove or a diamond pattern-shaped groove.

9. A method of fabricating a piezoelectric microphone, comprising:

the method comprises the following steps:

s1: depositing a layer of piezoelectric material on a substrate, and fixing the piezoelectric material on the substrate material;

s2: dividing a first sub-vibrating diaphragm and a second sub-vibrating diaphragm on the piezoelectric material, fixing one end of each sub-vibrating diaphragm with the substrate to form a fixed end, and enabling the other end of each sub-vibrating diaphragm to form a free movable end, wherein the width of the movable end is not less than that of the fixed end;

s3: generating an elastic expansion piece, wherein one end of the elastic expansion piece is connected with the movable end of the first sub-vibrating diaphragm, and the other end of the elastic expansion piece is connected with the second sub-vibrating diaphragm and/or the substrate;

s4: a back cavity having a polygonal shape is etched on the substrate.

10. The method of manufacturing according to claim 9, wherein:

in step S3, the elastic expansion piece is a hollow pattern on the piezoelectric cantilever diaphragm.

[ technical field ] A method for producing a semiconductor device

The present disclosure relates to piezoelectric microphones, and particularly to a piezoelectric microphone with a diaphragm having a large moment.

[ background of the invention ]

Microphones are of a wide variety, including moving coil, condenser, aluminum ribbon, carbon, and the like, and in mobile applications, Electret (ECM) condenser microphones and micro-electromechanical (MEMS) microphones are also common. The micro-electro-mechanical microphone is small in appearance, and has stronger heat resistance, vibration resistance and radio frequency interference resistance compared with an electret microphone. In addition, the mems microphones can be manufactured by a fully automated Surface Mount Technology (SMT), and most electret microphones require manual soldering.

The micro-electromechanical microphone is divided into a capacitance type microphone and a piezoelectric type microphone. The piezo-electric ratio is updated. The main advantage of piezoelectric technology is robustness against environmental influences, while capacitive technology suffers from performance degradation over time: in a condenser microphone, the performance of the microphone will change if there is particulate contamination between the diaphragm and the backplate. Another advantage of piezoelectric microphones is the higher signal-to-noise ratio (SNR), which currently can be achieved according to known methods over 75dB, theoretically even over 80 dB.

However, the width of the free end of the cantilever beam of the piezoelectric microphone with the existing structure is smaller than that of the fixed end, the generated moment under the action of sound pressure is lower, the signal to noise ratio is lower, and the free end is warped under the residual stress to generate a larger gap, so that the low-frequency performance of the microphone is influenced.

[ summary of the invention ]

The invention aims to provide a piezoelectric microphone, and in one aspect of the invention, the piezoelectric microphone comprises a substrate with a back cavity and a piezoelectric cantilever beam diaphragm fixed above the substrate; the piezoelectric type microphone also comprises an elastic expansion piece, one end of the elastic expansion piece is connected with the movable end of the first sub vibrating diaphragm, and the other end of the elastic expansion piece is connected with the second sub vibrating diaphragm and/or the substrate.

Preferably, the back cavity is square, and the elastic expansion piece connecting the first sub-diaphragm and the second sub-diaphragm is located on the central axis of the square and parallel to the fixed ends of the first sub-diaphragm and the second sub-diaphragm.

Preferably, the back cavity is octagonal, and the elastic expansion piece connecting the first sub-diaphragm and the second sub-diaphragm is located on the central axis of the octagonal shape and is parallel to the fixed ends of the first sub-diaphragm and the second sub-diaphragm.

Preferably, the back cavity is hexagonal, and the elastic expansion piece connecting the first sub-diaphragm and the second sub-diaphragm is located on the central axis of the hexagon and is parallel to the fixed ends of the first sub-diaphragm and the second sub-diaphragm.

Preferably, the back cavity is cross-shaped, and the elastic expansion piece connecting the first sub-diaphragm and the second sub-diaphragm is located on the cross-shaped central axis and is parallel to the fixed ends of the first sub-diaphragm and the second sub-diaphragm.

Preferably, the resilient bellows is of a flexible spring construction.

Preferably, the elastic expansion piece is a hollow pattern on the sub-diaphragm.

Preferably, the hollow pattern comprises a square groove, a Chinese character 'Wan' shaped groove or a diamond-shaped groove

In another aspect of the present invention, a method for manufacturing a piezoelectric microphone is provided, including the steps of:

s1: depositing a layer of piezoelectric material on a substrate to fix the piezoelectric material on the substrate material;

s2: dividing a first sub-vibration film and a second sub-vibration film on the piezoelectric material, fixing one end of each sub-vibration film with the substrate to form a fixed end, and forming a free movable end at the other end, wherein the width of the movable end is not less than that of the fixed end;

s3: generating an elastic telescopic piece, wherein one end of the elastic telescopic piece is connected with the movable end of the first sub-vibrating diaphragm, and the other end of the elastic telescopic piece is connected with the second sub-vibrating diaphragm and/or the substrate;

s4: a back cavity having a polygonal shape is etched in a substrate.

Preferably, in step S3, the elastic expansion element is a hollow pattern on the sub-diaphragm.

The technical scheme of the invention has the following beneficial technical effects: the width of the movable end of the cantilever beam in the piezoelectric microphone structure is not less than that of the fixed end, and larger moment is generated under the action of sound pressure, so that the signal-to-noise ratio of the microphone is improved; the flexible spring structure is arranged at the free movement edge of the cantilever beam, so that when the cantilever beam warps, the spring deforms along with the cantilever beam, gaps are avoided, and the low-frequency performance of the microphone is improved.

[ description of the drawings ]

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a top view of an embodiment of the present invention and an enlarged view of the resilient telescoping member;

FIG. 2 is a top view of various embodiments of the present invention;

FIG. 3 is a perspective view of one embodiment of the present invention;

FIG. 4(a) is a schematic view of the prior art without the elastic expansion member; FIG. 4(b) is a functional schematic view of the elastic expansion piece of the present invention and an enlarged view thereof.

[ detailed description ] embodiments

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only.

Referring to fig. 1 and 3, the present invention provides a piezoelectric microphone 100 comprising a substrate 10 having a back cavity 11, and a piezoelectric cantilever diaphragm 20 fixed above the substrate 10. The piezoelectric cantilever diaphragm 20 includes a pair of first sub-diaphragms 21 and a pair of second sub-diaphragms 22 which are arranged oppositely, and the pair of sub-diaphragms of the piezoelectric cantilever diaphragm 20 can deform under the action of external sound pressure and generate a piezoelectric effect to generate an electrical signal for outputting. The back cavity 11 is a cavity formed by the substrate 10 and the piezoelectric cantilever diaphragm 20, and due to the existence of the back cavity 11, when the same sound intensity acts on the piezoelectric cantilever diaphragm 20, the vibration displacement of the piezoelectric cantilever diaphragm 20 is greatly improved, so that the strain degree is enhanced to generate more charges. The first sub-diaphragm 21 and the second sub-diaphragm 22 have the same shape, and each sub-diaphragm has at least one fixed end 211, 221 fixed on the base 10 and at least one movable end 212, 222 connected to the other sub-diaphragm through the elastic expansion member 30. The elastic expansion piece 30, the first sub-diaphragm 21, and the second sub-diaphragm 22 are connected to the substrate 10, and the fixed ends of the first sub-diaphragm 21 and the second sub-diaphragm 22 form certain constraints on the first sub-diaphragm 21 and the second sub-diaphragm 22, so that the first sub-diaphragm 21 and the second sub-diaphragm 22 are suspended above the back cavity 11 of the substrate 10, and the two first sub-diaphragm 21 and the two second sub-diaphragm 22 are located on the same plane as much as possible, thereby reducing the decrease of the signal-to-noise ratio caused by the deformation of the two first sub-diaphragm 21 and the second sub-diaphragm 22. In addition, in order to further improve the signal-to-noise ratio, the length of the movable ends 212 and 222 of the sub-diaphragms is not smaller than that of the fixed ends 211 and 221.

The material of the substrate 10 may be a silicon material or the like that can be processed using an etching process to etch the back cavity 11 on the substrate of the substrate 10. The material of the piezoelectric cantilever diaphragm 20 is a ceramic material capable of generating a piezoelectric effect, such as AlN, perovskite oxide, and the like. The material of the piezoelectric cantilever diaphragm 20 may be deposited on the base by physical vapor deposition or the like.

In order to further improve the stability of the piezoelectric cantilever diaphragm 20, in a preferred embodiment, the piezoelectric cantilever diaphragm 20, except for the fixed ends 211 and 221 of the first and second sub-diaphragms 21 and 22, is connected to the base 10 by using the elastic expansion member 30. In this preferred embodiment, the piezoelectric cantilever diaphragm 20 is attached to the base 10 on all sides, which can further improve stability.

In one embodiment, the piezoelectric cantilever diaphragm 20 includes at least three layers, each of which includes a first electrode plate, a piezoelectric membrane, and a second electrode plate stacked in sequence along the vibration direction, where the first electrode plate is disposed on one side of the piezoelectric cantilever diaphragm 20 close to the back cavity 11. More specifically, the piezoelectric cantilever diaphragm 20 may also be a five-layer structure or a multi-layer structure.

In a specific embodiment, as shown in fig. 4(b), the elastic expansion member 30 is a flexible spring structure, which can deform the spring together with the piezoelectric cantilever diaphragm 20 when the base 10 and the piezoelectric cantilever diaphragm 20 are connected and the two first sub-diaphragms 21 and the two second sub-diaphragms 22 are connected, so as to avoid the gap shown in fig. 4(a), thereby improving the low-frequency performance of the microphone.

In a specific embodiment, as can be seen from the enlarged portion in fig. 1, the flexible spring structure as the elastic expansion member 30 is a hollow pattern etched on the first sub-diaphragm 21 and the second sub-diaphragm 22. Specifically, the hollow pattern may be a zigzag groove, or a rhombus groove. Specifically, the hollow pattern is etched on the piezoelectric cantilever diaphragm 20 deposited on the base by a physical vapor deposition method or the like by photolithography.

In an alternative embodiment, the desired movable ends 212, 222 and the portion of the piezoelectric cantilever diaphragm 20 that is attached to the base 10 may be etched directly into a single, deposited piece of the piezoelectric cantilever diaphragm 20.

The invention also provides a method for manufacturing the piezoelectric microphone, which comprises the following steps:

s1: a layer of piezoelectric material is deposited on a substrate such that the piezoelectric material is fixed to the substrate material.

S2: and dividing a first sub-vibrating diaphragm 21 and a second sub-vibrating diaphragm 22 on the piezoelectric material, fixing one end of each sub-vibrating diaphragm with the substrate 10 to form a fixed end, and forming a free movable end at the other end, wherein the width of the movable end is not less than that of the fixed end.

On the first sub-diaphragm 21 and the second sub-diaphragm 22, the sides of the first sub-diaphragm 21 and the second sub-diaphragm 22 connected to each other by the flexible spring structure 30 are set as movable ends 212 and 222, and the sides parallel to the movable ends 212 and 222 and fixed on the substrate 10 are set as fixed ends.

S3: an elastic expansion member 30 is formed, and one end of the elastic expansion member 30 is connected to the movable end 212 of the first sub-diaphragm 21, and the other end is connected to the second sub-diaphragm 22 and/or the substrate 10.

S4: a back cavity 11 having a polygonal shape is etched in the base material.

The shape of the back cavity 11 determines the shape of the piezoelectric cantilever diaphragm 20 overlying the substrate 10, and therefore it is desirable to ensure that the length of the movable end 212, 222 of the sub-diaphragm 21, 22 is not less than the length of the fixed end 211, 221.

In an alternative embodiment, in step S3, the elastic expansion member is a hollow pattern on the piezoelectric cantilever diaphragm.

While various embodiments of piezoelectric microphone 100 having different back cavity 11 shapes are described below with reference to fig. 2, it should be noted that the following embodiments are only intended to specifically illustrate the structure of piezoelectric microphone 100 according to the present invention, and do not limit the present invention in any way.

Example 1

Referring to fig. 2(a), in a specific embodiment, a pair of first and second sub-diaphragms 21 and 22 having the same shape form a piezoelectric cantilever diaphragm 20 fixedly suspended above the back cavity 11 of the substrate 10 having the octagonal shape to receive external sound pressure and convert it into an electrical signal. Specifically, the movable ends 212 and 222 of the first and second sub-diaphragms 21 and 22 are connected to each other by the elastic expansion member 30 along the central axis of the octagonal shape of the back cavity 11, so that the first and second sub-diaphragms 21 and 22 are connected to form the piezoelectric cantilever diaphragm 20, and the fixed ends 211 and 221 of the first and second sub-diaphragms 21 and 22 are located on two sides parallel to and opposite to the central axis among eight sides and are fixedly connected to the substrate 10. In this embodiment, the lengths of the movable ends 212 and 222 of the first sub-diaphragm 21 and the second sub-diaphragm 22 are greater than the lengths of the fixed ends 211 and 221, so that the piezoelectric cantilever diaphragm 20 has a larger moment under the action of sound pressure, and the signal-to-noise ratio can be improved.

Example 2

Referring to fig. 2(b), in a specific embodiment, a pair of first and second sub-diaphragms 21 and 22 having the same shape form a piezoelectric cantilever diaphragm 20 fixedly suspended above the back cavity 11 of the substrate 10 having a hexagonal shape to receive external sound pressure and convert it into an electrical signal. Specifically, the movable ends 212 and 222 of the first and second sub-diaphragms 21 and 22 are connected to each other through the elastic expansion member 30 along the central axis of the hexagon, so that the first and second sub-diaphragms 21 and 22 are connected to form the piezoelectric cantilever diaphragm 20, and the fixed ends 211 and 221 of the first and second sub-diaphragms 21 and 22 are located on two sides parallel to and opposite to the central axis among six sides and are fixedly connected to the substrate 10. In this embodiment, the lengths of the movable ends 212 and 222 of the first sub-diaphragm 21 and the second sub-diaphragm 22 are not less than the lengths of the fixed ends 211 and 221, so that the piezoelectric cantilever diaphragm 20 has a larger moment under the action of sound pressure, and the signal-to-noise ratio can be improved.

Example 3

Referring to fig. 2(c), in a specific embodiment, a pair of first and second sub-diaphragms 21 and 22 having the same shape form a piezoelectric cantilever diaphragm 20 fixedly suspended above the back cavity 11 of the substrate 10 having a cross shape to receive external sound pressure and convert it into an electrical signal. Specifically, the movable ends 212 and 222 of the first sub-diaphragm 21 and the second sub-diaphragm 22 are connected to each other through the elastic expansion member 30 along the cross central axis, so that the first sub-diaphragm 21 and the second sub-diaphragm 22 are connected to form the piezoelectric cantilever diaphragm 20, and the fixed ends 211 and 221 of the first sub-diaphragm 21 and the second sub-diaphragm 22 are located on two sides parallel to and opposite to the cross central axis and are fixedly connected to the substrate 10. It can be seen that, in this embodiment, the lengths of the movable ends 212 and 222 of the first sub-diaphragm 21 and the second sub-diaphragm 22 are not less than the lengths of the fixed ends 211 and 221, which enables the piezoelectric cantilever diaphragm 20 to have a larger moment under the action of sound pressure, and can improve the signal-to-noise ratio.

Example 4

Referring to fig. 2(d), in a specific embodiment, a pair of first and second sub-diaphragms 21 and 22 having the same shape form a piezoelectric cantilever diaphragm 20 fixedly suspended above the back cavity 11 having a square shape of the substrate 10 to receive external sound pressure and convert it into an electrical signal. Specifically, the movable ends 212 and 222 of the first sub-diaphragm 21 and the second sub-diaphragm 22 are connected to each other through the elastic expansion member 30 along the central axis of the square, so that the first sub-diaphragm 21 and the second sub-diaphragm 22 are connected to form the piezoelectric cantilever diaphragm 20, and the fixed ends 211 and 221 of the first sub-diaphragm 21 and the second sub-diaphragm 22 are located on two sides parallel to and opposite to the central axis of the square and are fixedly connected to the substrate 10.

In this embodiment, the piezoelectric cantilever diaphragm 20 is also connected using the elastic expansion member 30, except for the fixed ends 211, 221 of the first and second sub-diaphragms 21, 22, which are adjacent to the base 10.

In this embodiment, the lengths of the movable ends 212 and 222 of the first sub-diaphragm 21 and the second sub-diaphragm 22 are greater than the lengths of the fixed ends 211 and 221, so that the piezoelectric cantilever diaphragm 20 has a larger moment under the action of sound pressure, and the signal-to-noise ratio can be improved.

The technical features of the above embodiments may be arbitrarily combined, and for the sake of brief description, all possible combinations of the technical features in the above embodiments are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features. Finally, it should also be noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

The above examples only show some embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.