CN111048660A

CN111048660A - Piezoelectric transducer, method of manufacturing piezoelectric transducer, and electronic apparatus

Info

Publication number: CN111048660A
Application number: CN202010168869.2A
Authority: CN
Inventors: 罗松成; 陈昱辰; 方维伦
Original assignee: Gettop Acoustic Co Ltd
Current assignee: Gettop Acoustic Co Ltd
Priority date: 2020-03-12
Filing date: 2020-03-12
Publication date: 2020-04-21
Anticipated expiration: 2040-03-12
Also published as: CN111048660B

Abstract

The invention relates to a piezoelectric transducer, a method for preparing the piezoelectric transducer and an electronic device. A piezoelectric transducer comprises a support structure and a piezoelectric diaphragm arranged on the support structure; the piezoelectric diaphragm comprises at least two adjacent diaphragms, and a gap is formed between the two adjacent diaphragms; the fixed edge of the diaphragm is supported by the supporting structure, and the part of the diaphragm which is not fixed is a free end; and for two adjacent diaphragms, the direction pointing to the free end of one diaphragm along the fixed edge of the one diaphragm is a first direction, and the tail end of the free end of the one diaphragm in the first direction is opposite to the adjacent side edge of the fixed edge of the other diaphragm. The piezoelectric transducer, the method for preparing the piezoelectric transducer and the electronic equipment can improve the phenomenon of gap enlargement between the diaphragms of the traditional piezoelectric transducer, and are particularly favorable for reducing the loss of low-frequency sensitivity of the piezoelectric transducer when the piezoelectric transducer is a piezoelectric electroacoustic transducer.

Description

Piezoelectric transducer, method of manufacturing piezoelectric transducer, and electronic apparatus

Technical Field

The present invention relates to the field of electronic technologies, and in particular, to a piezoelectric transducer, a method for manufacturing the piezoelectric transducer, and an electronic device.

Background

When piezoelectric transducer is prepared, the residual stress of the film stack is not easy to control in the process of manufacturing the piezoelectric diaphragm, so that the stress of the whole-film piezoelectric transducer cannot be released, and therefore, the rigidity of the piezoelectric diaphragm can be increased, and the sensitivity of the piezoelectric transducer is reduced.

The traditional solution is to make the piezoelectric diaphragm into a plurality of cantilever beam structures to release the residual stress, so as to improve the sensitivity of the piezoelectric transducer. Specifically, the piezoelectric diaphragm comprises at least two diaphragms, one end of each diaphragm is fixed on the supporting structure, the other end of each diaphragm is a free end, and the supporting structure is provided with a back cavity to expose the free end of each diaphragm, so that each diaphragm and the supporting structure form a cantilever beam structure respectively. However, when the free ends of two adjacent membranes in the conventional piezoelectric transducer are arranged oppositely, the gap between the two adjacent membranes is enlarged because the cantilever beam structure causes out-of-plane deformation due to the release of residual stress, and particularly when the piezoelectric transducer is a piezoelectric electroacoustic transducer, the enlargement of the gap between the membranes easily reduces the acoustic resistance, which brings loss of low-frequency sensitivity of the piezoelectric electroacoustic transducer.

Disclosure of Invention

In view of the above, it is desirable to provide a piezoelectric transducer, a method of manufacturing the piezoelectric transducer, and an electronic apparatus.

A piezoelectric transducer comprises a support structure and a piezoelectric diaphragm arranged on the support structure; the piezoelectric diaphragm comprises at least two adjacent diaphragms, and a gap is formed between the two adjacent diaphragms; the fixed edge of the diaphragm is supported by the supporting structure, and the part of the diaphragm which is not fixed is a free end;

and for two adjacent diaphragms, the direction pointing to the free end of one diaphragm along the fixed edge of the one diaphragm is a first direction, and the tail end of the free end of the one diaphragm in the first direction is opposite to the adjacent side edge of the fixed edge of the other diaphragm.

In one embodiment, the fixed edges of two adjacent diaphragms form an included angle, and the included angle is larger than 0 degree and smaller than 180 degrees.

In one embodiment, the fixing edges of two adjacent diaphragms are perpendicular to each other.

In one embodiment, the number of the diaphragms is four, and the four diaphragms are arranged in two rows and two columns.

In one embodiment, the support structure includes a substrate and a sacrificial layer disposed on the substrate, the sacrificial layer being disposed adjacent to the piezoelectric diaphragm;

wherein, back cavities are arranged on the substrate and the sacrificial layer to expose the free ends of the diaphragms.

In one embodiment, the cross section of the back cavity is square, and the diaphragm is a rectangular diaphragm.

In one embodiment, the free ends of the diaphragms are identical in shape and area.

In one embodiment, the piezoelectric diaphragm includes a first electrode layer, a piezoelectric material layer, and a second electrode layer sequentially stacked on the support structure; the piezoelectric material layer is provided with a through hole so as to lead out the first electrode layer;

the second electrode layer comprises a second electrode, a second electrode leading-out end and a first electrode leading-out end;

the second electrode is electrically connected with the second electrode leading-out end;

the first electrode layer comprises a first electrode, and the first electrode leading-out end is electrically connected with the first electrode through a through hole in the piezoelectric material layer.

In one embodiment, the piezoelectric diaphragm further includes a flexible thin film layer and/or an insulating layer sequentially stacked and disposed between the support structure and the first electrode layer.

A method of making a piezoelectric transducer, the method comprising:

providing a support structure;

forming a piezoelectric diaphragm on the support structure;

etching the supporting structure to form a back cavity so as to expose part of the piezoelectric diaphragm;

a gap is formed in the piezoelectric diaphragm at a position opposite to the back cavity, so that the piezoelectric diaphragm comprises at least two adjacent diaphragms, the fixed edges of the diaphragms are supported by the supporting structure, and the parts of the diaphragms which are not fixed are free ends;

In one embodiment, the step of forming a slit in the piezoelectric diaphragm at a position opposite to the back cavity includes:

and swastika-shaped gaps are formed in the piezoelectric diaphragm at the position opposite to the back cavity.

An electronic device comprising a piezoelectric transducer as claimed in any one of the above.

According to the piezoelectric transducer, the preparation method and the electronic equipment, when the cantilever beam structure is used for releasing the residual stress of the piezoelectric diaphragm, the direction pointing to the free end of one diaphragm along the fixed edge of the diaphragm is the first direction for two adjacent diaphragms, and the tail end of the free end of the diaphragm in the first direction is opposite to the adjacent side edge of the fixed edge of the other diaphragm, so that when two adjacent diaphragms deform out of a plane, the gaps between the two diaphragms are reduced due to different warping directions of the free ends of the two diaphragms, and especially when the piezoelectric transducer is a piezoelectric electroacoustic transducer, the high sensitivity of the piezoelectric transducer is ensured, and meanwhile, the low-frequency sensitivity loss cannot be caused.

For example, an included angle between the fixing edges of two adjacent diaphragms is greater than 0 degree and less than 180 degrees; for example, the fixing edges of two adjacent diaphragms are perpendicular to each other, so that the gap between the two diaphragms can be further reduced. The number of the membranes can be four, the four membranes are arranged in two rows and two columns, and the four membranes can be mutually vertically staggered, so that gaps after the membranes are warped are shielded, and the loss of the low-frequency sensitivity of the piezoelectric electroacoustic transducer is further reduced.

The supporting structure comprises a substrate and a sacrificial layer on the substrate, wherein a back cavity is formed in the substrate and the sacrificial layer to expose a part of the piezoelectric vibrating diaphragm, and a gap is formed in the piezoelectric vibrating diaphragm to enable the cantilever beam structure to release the residual stress of the piezoelectric vibrating diaphragm, so that the piezoelectric vibrating diaphragm is not easy to warp. The cross section of the back cavity can be square, so that each diaphragm is a rectangular diaphragm, the shape and the area of the free end of each diaphragm can be set to be equal, the preparation process is relatively simple, and the cost is reduced.

The piezoelectric material layer comprises a first electrode layer, a piezoelectric material layer and a second electrode layer which are sequentially arranged on the supporting structure, a second electrode leading-out end and a first electrode leading-out end are arranged on the second electrode layer, the first electrode layer is led out by arranging a through hole on the piezoelectric material layer, so that the piezoelectric material layer is easy to be electrically connected with the second electrode on the second electrode layer, and wiring does not need to be arranged on the side surface; the first electrode leading-out end is connected with the first electrode, and the second electrode is connected with the second electrode leading-out end, so that the external signal processing circuit is directly connected with the first electrode leading-out end and the second electrode leading-out end on the surface of the piezoelectric diaphragm, and the wiring is more regular.

The piezoelectric diaphragm can further comprise a flexible thin film layer which is sequentially stacked and arranged between the supporting structure and the first electrode layer, and the flexible thin film layer is favorable for driving the deformation of the piezoelectric material layer so as to improve the signal-to-noise ratio of the piezoelectric electroacoustic transducer.

Drawings

Fig. 1 is a perspective view of a piezoelectric transducer in one embodiment.

Fig. 2 is a perspective view of a cantilever beam structure in a piezoelectric transducer in one embodiment.

Fig. 3 is a top view of a piezoelectric transducer in an embodiment.

Fig. 4 is a cross-sectional view along direction AA' of the piezoelectric diaphragm of the piezoelectric transducer in the embodiment of fig. 3, when the free end of the piezoelectric diaphragm is warped.

Fig. 5 is a cross-sectional view of a conventional piezoelectric transducer.

Fig. 6 is a cross-sectional view of a piezoelectric transducer in an embodiment.

Fig. 7 is a flow diagram of a method of making a piezoelectric transducer in one embodiment.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

In the description of the present application, it is to be understood that the terms "center", "lateral", "upper", "lower", "left", "right", "vertical", "horizontal", "top", "bottom", "inner" and "outer" etc. indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present application and simplifying the description, but do not indicate or imply that the referred device or element must have a particular orientation, be constructed in a particular orientation, and be operated, and thus should not be construed as limiting the present application. Further, when an element is referred to as being "formed on" another element, it can be directly connected to 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. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present.

The application provides a piezoelectric transducer based on cantilever beam structure to utilize the residual stress of cantilever beam structure release piezoelectricity vibrating diaphragm in order to guarantee the higher sensitivity of piezoelectric transducer, this piezoelectric transducer can also improve the phenomenon that the gap enlarges between the diaphragm simultaneously, is favorable to avoiding the loss of its low frequency sensitivity especially when piezoelectric transducer is piezoelectric transducer. The piezoelectric transducer may further include other devices such as an integrated circuit to form a MEMS (Micro-Electro-Mechanical System) piezoelectric transducer.

Fig. 1 is a perspective view of a piezoelectric transducer in an embodiment, and fig. 2 is a perspective view of a cantilever beam structure in the piezoelectric transducer in an embodiment. As shown in fig. 1 and 2, the piezoelectric transducer 100 includes a support structure 110 and a piezoelectric diaphragm 120 disposed on the support structure 110. The piezoelectric diaphragm 120 includes at least two adjacent membranes a, the fixed edges of the membranes a are supported by the support structure 110, and the unfixed portions of the membranes a are free ends, so that each membrane a forms a cantilever beam structure with the support structure 110, respectively, to release the residual stress of the piezoelectric diaphragm 120, thereby ensuring higher sensitivity of the piezoelectric transducer 100.

In the present embodiment, the gap 129 is provided between the adjacent two diaphragms a, so that the work between the two diaphragms a does not interfere with each other, and the expansion of the gap 129 between the adjacent two diaphragms a can be avoided by the following modification. It should be noted that the width of the gap 129 needs to be made very small. Illustratively, the width of the gap 129 is less than 5um to avoid severe low frequency attenuation when the piezoelectric transducer 100 is a piezoelectric electroacoustic transducer.

Wherein, for two adjacent diaphragms a, the direction pointing to the free end of one diaphragm a along the fixed edge of the diaphragm a is a first direction, and the tail end of the free end of the diaphragm a in the first direction is opposite to the adjacent side edge of the fixed edge of the other diaphragm a.

Specifically, referring to fig. 3, the diaphragm a1 and the diaphragm a2 are illustrated as being adjacent to each other. The fixed edge of the diaphragm a2 is L2, the direction m2 of the fixed edge L2 of the diaphragm a2 pointing to the free end thereof is a first direction (opposite direction to the X direction), the fixed edge of the diaphragm a1 is L1, and the adjacent side edge of the fixed edge L1 of the diaphragm a1 is opposite to the end of the free end of the diaphragm a2 in the opposite direction to the X direction. For example, the fixed side L1 of the patch a1 and the fixed side L2 of the vertical patch a2 are perpendicular to each other such that the adjacent side of the fixed side L1 of the patch a1 is disposed opposite to the end of the free end of the patch a2 in the first direction. In other embodiments, there may be other angles between the fixed edge L1 of patch a1 and the fixed edge L2 of patch a2 other than 90 °. It is noted that the angle is greater than 0 degrees and less than 180 degrees.

It will be appreciated that when the cantilever beam structure induces a release of residual stress causing out-of-plane deformation, the diaphragm typically undergoes an increasing degree of warping in the free end along the fixed edge in the direction of the free end. Still referring to fig. 3, the free end of the membrane a1 is warped in the direction m1 to a gradually increasing extent and the free end of the membrane a2 is warped in the direction m2 to a gradually increasing extent. Referring to fig. 4 again, even if the diaphragm a1 is deformed in a plane due to the release of residual stress, since the diaphragm a1 is fixed to the side L1, and the direction m1 along the fixed side toward the free end (hereinafter referred to as the extending direction of the free end) faces into the paper, the warping of the free end of the diaphragm a1 does not affect the width of the gap 129 between the diaphragm a1 and the diaphragm a2 as seen from the angle of fig. 4; when the diaphragm a2 is deformed in a plane due to the release of residual stress, since the diaphragm a2 is fixed to the side L2 and the free end extends in the direction of m2, it can be seen from the perspective of fig. 4 that the width of the gap 129 between the diaphragm a1 and the diaphragm a2 is related to the degree of warpage of the diaphragm a2 and the original width of the gap 129, and the width of the gap 129 becomes d.

Fig. 5 is a cross-sectional view of a conventional piezoelectric transducer. As shown in fig. 5, it can be seen that two diaphragms b1 and b2 in the conventional transducer are oppositely arranged, the extending direction of the free end of the diaphragm b1 is n1, the extending direction of the free end of the diaphragm b2 is n2, and the n1 direction and the n2 direction are just opposite directions, so that the width of the gap between the diaphragm b1 and the diaphragm b2 is determined by the original width of the gap, the warping degree of the diaphragm b1 and the warping degree of the diaphragm b2 from the perspective of fig. 5. Assuming that the other conditions of the conventional piezoelectric transducer are the same as in the embodiment of fig. 4 and neglecting the original width of the inter-diaphragm gap, the gap width between diaphragm b1 and diaphragm b2 is approximately 2 d.

Obviously, the piezoelectric transducer 100 provided in the above embodiment improves the problem of the expansion of the gap between the diaphragms of the conventional piezoelectric transducer, so that the loss of the low-frequency sensitivity of the piezoelectric transducer 100 can be reduced while ensuring the high sensitivity of the piezoelectric transducer 100 by using the cantilever beam structure, especially when the piezoelectric transducer 100 is a piezoelectric electroacoustic transducer.

Further, referring to fig. 1 and 3, the number of the patches a is four, and includes the patches a1, a2, a3 and a4 arranged in two rows and two columns. The diaphragms a1, a2, a3 and a4 can be further arranged perpendicularly and alternately, so that the extending directions of the free ends of two adjacent diaphragms a are perpendicular to each other, and the gaps 129 after being warped are shielded, thereby further reducing the loss of the low-frequency sensitivity of the piezoelectric electroacoustic transducer. It should be noted that the number of the diaphragms a of the piezoelectric transducer 100 is not limited to four, as long as at least two adjacent diaphragms a are ensured.

In particular, and still referring to FIG. 3, the relationship of adjacent patch a1 to patch a2 has been described in the above embodiments. For the other two diaphragms a3 and a4, the fixed edge of the diaphragm a3 is L3, and the extending direction of the free end of the diaphragm a is m 3; the fixed edge of the membrane a4 is L4, and the extending direction of the free end of the membrane a4 is m 4. In this embodiment, the X direction and the Y direction are perpendicular to each other, the m1 direction is the same as the X direction, the m2 direction is opposite to the Y direction, the m3 direction is the same as the Y direction, and the m4 direction is opposite to the X direction.

The membrane a1 is also adjacent to the membrane a3, the fixed side L1 of the membrane a1 is perpendicular to the fixed side L3 of the membrane a3, so that their free end extension directions m1 and m3 are perpendicular to each other, so that the width of the gap 129 between the membrane a1 and the membrane a3 is not enlarged by the warping of the membrane a 3; similarly, the patch a3 is also adjacent to the patch a4, and the fixed side L3 of the patch a3 is perpendicular to the fixed side L4 of the patch a4, so that their free end extension directions m3 and m4 are perpendicular to each other, so that the width of the gap 129 between the patch a3 and the patch a4 is not enlarged by the warpage of the patch a 4; similarly, the patch a4 is also adjacent to the patch a2, and the fixed side L2 of the patch a2 is perpendicular to the fixed side L4 of the patch a4, so that their free end extension directions m2 and m4 are perpendicular to each other, so that the width of the gap 129 between the patch a3 and the patch a4 is not enlarged by the warpage of the patch a 2. Therefore, the diaphragms a1, a2, a3 and a4 are vertically staggered to block the warped gaps 129, which is beneficial to reduce the loss of low-frequency sensitivity when the piezoelectric transducer 100 is a piezoelectric electroacoustic transducer.

In one embodiment, referring to fig. 6, the support structure 110 includes a substrate 114 and a sacrificial layer 116 disposed on the substrate 114. The sacrificial layer 116 is disposed adjacent to the piezoelectric diaphragm 120.

The substrate 114 may be made of silicon material, and the silicon has the characteristics of high strength, good wear resistance, and the like, so as to better support the piezoelectric diaphragm 120. Etching vias in the substrate 114 using conventional etching techniques, e.g., deep ion reactive etching; or the support structure 110 may further include a mask 112 disposed on a side of the substrate 114 away from the sacrificial layer 116, and the substrate 114 is subjected to photolithography by using the mask 112, so as to strictly control the position and size of the etched through hole on the substrate 114.

The sacrificial layer 116 may be silicon dioxide, etc., so that the sacrificial layer 116 may act as a barrier layer when the substrate 114 is etched. After the etching of the substrate 114 is completed, the corresponding portion of the sacrificial layer 116 is removed, thereby forming a back cavity 119 on the substrate 114 and the sacrificial layer 116. For example, the sacrificial layer 116 is wet-etched using a hydrofluoric acid (HF) solution.

The back cavities 119 formed in the substrate 114 and the sacrificial layer 116 can expose the free ends of the membranes a, so that the membranes a and the support structure 110 form a cantilever structure.

In this embodiment, the cross section of the back cavity 119 is square, and the diaphragm a is a rectangular diaphragm, so that the preparation process is simple and the cost is low. When the number of the diaphragms a is four, the fixed sides of the four diaphragms a are respectively located on four sides of the back cavity 119. Furthermore, the shape and area of the free end of each diaphragm a are the same, so that when the piezoelectric transducer 100 is a piezoelectric electroacoustic transducer, each diaphragm a can capture or emit sound waves of the same frequency band, the sensitivity of the piezoelectric electroacoustic transducer to the sound waves of the frequency band is enhanced, and the signal-to-noise ratio is improved. For example, the four diaphragms a in this embodiment can be realized by forming swastika-shaped slits 129 in the piezoelectric diaphragm 120 at positions opposite to the back cavity 119.

In other embodiments, the back cavity 119 may also have a circular cross-section, and the diaphragm a is a conical diaphragm; or the cross section of the back cavity 119 may have other irregular shapes, etc.

In one embodiment, still referring to FIG. 6, a piezoelectric diaphragm 120 is formed by sequentially stacking a first electrode layer 122, a piezoelectric material layer 124, and a second electrode layer 126 disposed on a support structure 110. The piezoelectric material layer 124 is provided with a through hole for leading out the first electrode layer 122.

Further, referring to fig. 1 and 6, the second electrode layer 126 includes a second electrode 1262, a second electrode terminal 1264, and a first electrode terminal 1266. The second electrode 1262 is electrically connected to a second electrode terminal 1264. The first electrode layer 122 includes a first electrode 1222, and a first electrode lead 1266 is electrically connected to the first electrode 1222 through a through hole in the piezoelectric material layer 124. Illustratively, the second electrodes 1262 are disposed at the free ends of the diaphragms a, the second electrodes 1262 are rectangular, and the second electrodes 1262 are vertically staggered in the same plane.

In this embodiment, the piezoelectric transducer 100 can further include a signal processing circuit (not shown) coupled to the first electrode terminal 1266 and the second electrode terminal 1264. For example, when the piezoelectric transducer 100 is applied to a microphone, after being pushed by air pressure or sound pressure, the free end of the diaphragm a deforms, and the piezoelectric material layer 124 converts the deformation energy into electric charge transfer due to the positive piezoelectric effect, so that an electric signal is output between the first electrode 1222 and the second electrode 1262 and is transmitted to a signal processing circuit through the first electrode leading-out terminal 1266 and the second electrode leading-out terminal 1264 for processing, thereby realizing detection of a sound wave; when the piezoelectric transducer 100 is applied to a speaker, the signal processing circuit outputs electrical signals to the first electrode 1222 and the second electrode 1262 through the first electrode terminal 1266 and the second electrode terminal 1264, and the piezoelectric material layer 124 converts the charge transfer into deformation energy due to the inverse piezoelectric effect, so that the free end of the diaphragm a is deformed, and sound waves are emitted.

Further, the piezoelectric diaphragm 120 may further include a flexible film layer 128 and/or an insulating layer 127 sequentially stacked and disposed between the support structure 110 and the first electrode layer 122. Optionally, the flexible thin film layer 128 is made of a silicon material, and the flexible thin film layer 128 is beneficial to driving the piezoelectric material layer 124 to deform, so that when the piezoelectric transducer 100 is a piezoelectric electroacoustic transducer, the sensitivity of the piezoelectric transducer under low voltage can be further improved. In this embodiment, the flexible thin film layer 128 and the substrate 114 are made of silicon materials, so that the sacrificial layer 116 can prevent the flexible thin film layer 128 from being damaged when the substrate 114 is etched. The insulating layer 127 insulates the first electrode layer 122 from the support structure 110. The flexible thin film layer 128 and the insulating layer 127 also support the first electrode layer 122, the piezoelectric material layer 124, and the second electrode layer 126.

A method of making a piezoelectric transducer is also provided. As shown in fig. 7, the method of making a piezoelectric transducer includes the steps of:

and S110, providing a support structure.

For example, referring to fig. 6, the support structure 110 may include a substrate 114 and a sacrificial layer 116 formed on the substrate 114. Optionally, the substrate 114 is made of a silicon material, and the sacrificial layer 116 is made of a silicon dioxide material. In other embodiments, conventional implementation steps such as cleaning and drying can be added in the step as required.

And S120, forming a piezoelectric diaphragm on the supporting structure.

Illustratively, a deposition process is used to sequentially form the flexible thin film layer 128, the insulating layer 127, the first electrode layer 122, the piezoelectric material layer 124, and the second electrode layer 126 on the support structure 110. Wherein the flexible film layer 128 and the insulating layer 127 may be selectively omitted. In this step, patterning the first electrode layer 122 to form a first electrode 1222 may be further included; patterning the second electrode layer 126 to form a second electrode 1262, a second electrode terminal 1264, and a first electrode terminal 1266; forming a through hole in the piezoelectric material layer 124; a process of electrically connecting the first electrode terminal 1266 to the first electrode 1222 through a through hole in the piezoelectric material layer 124.

And S130, etching the support structure to form a back cavity so as to expose part of the piezoelectric diaphragm.

Specifically, the substrate 114 is etched to form a through hole at the position of the back cavity 119, and the sacrificial layer 116 serves as a barrier layer in this step; the corresponding portion of the sacrificial layer 116 is removed by wet etching or the like, so as to form a back cavity 119, so as to expose a portion of the piezoelectric diaphragm 120. The cross-section of the back cavity 119 may be circular, square, or other shape.

And S140, forming a gap on the piezoelectric diaphragm at the position opposite to the back cavity.

Specifically, a slit 129 is formed in the piezoelectric diaphragm 120 at a position opposite to the back cavity 119, so that the piezoelectric diaphragm 120 includes at least two adjacent membranes a. The fixed edge of membrane a is supported by support structure 110, and the portion of membrane a that is not fixed is the free end. And for two adjacent diaphragms a, the direction along which the fixed edge of one diaphragm a points to the free end of the diaphragm a is a first direction, and the tail end of the free end of the diaphragm a in the first direction is opposite to the adjacent side edge of the fixed edge of the other diaphragm a. For example, referring to fig. 3, swastika-shaped slits 129 are formed in the piezoelectric diaphragm 120 at a position opposite to the back cavity 119, so that the diaphragms a1, a2, a3 and a diaphragm a4 are formed in the same plane and are vertically staggered with each other, and the fixing edges of two adjacent diaphragms a are perpendicular to each other.

It is to be noted that the implementation steps in the method of manufacturing the piezoelectric transducer 100 provided in the above embodiments do not limit the implementation order. For example, the back cavity 119 may be formed on the support structure 110 after the step of removing a portion of the layer of piezoelectric material 124. In addition, the method for manufacturing a piezoelectric transducer provided in this embodiment can form the piezoelectric transducer 100 in any of the above embodiments, and the specific process is not described herein.

The application also provides an electronic device. The electronic device comprises a piezoelectric transducer 100 as described in any of the embodiments above. The electronic device may be a speaker, a microphone, a mobile phone, a digital camera, a notebook computer, a personal digital assistant, an MP3 player, a hearing aid, a television, a telephone, a conference system, a wired headset, a wireless headset, a recording pen, a recording device, a line controller, and so on.

When the cantilever beam structure is used for releasing the residual stress of the piezoelectric diaphragm 120, the direction pointing to the free end of one diaphragm a along the fixed edge of the diaphragm a is the first direction, and the tail end of the free end of the diaphragm a in the first direction is opposite to the adjacent side edge of the fixed edge of the other diaphragm a, so that when the two adjacent diaphragms a deform out of a plane, the gap 129 between the two diaphragms a is reduced due to different warping directions of the free ends of the two diaphragms a, and particularly when the piezoelectric transducer 100 is a piezoelectric transducer, the high sensitivity is ensured and low-frequency sensitivity loss is avoided; further, the fixing edges of two adjacent diaphragms a are perpendicular to each other, so that the gap 129 between the two diaphragms a is further reduced; the number of the membranes a can be four, and the four membranes a are arranged in two rows and two columns, namely the four membranes a are vertically staggered with each other, so that the gaps 129 after being warped are shielded, and the loss of the low-frequency sensitivity of the piezoelectric electroacoustic transducer is further reduced; the supporting structure 110 includes a substrate 114 and a sacrificial layer 116 on the substrate 114, the substrate 114 and the sacrificial layer 116 are provided with a back cavity 119 to expose a portion of the piezoelectric diaphragm 120, and since the piezoelectric diaphragm 120 is provided with a slit 129, a cantilever structure is formed to release the residual stress of the piezoelectric diaphragm 120, and the piezoelectric diaphragm 120 is not easily warped; the cross section of the back cavity 119 can be square, so that each diaphragm a is a rectangular diaphragm, the shape and the area of the free end of each diaphragm a can be set to be equal, the preparation process is relatively simple, and the cost is reduced; the piezoelectric material layer 124 comprises a first electrode layer 122, a piezoelectric material layer 124 and a second electrode layer 126 which are sequentially arranged on the support structure 110, a second electrode 1262, a second electrode leading-out terminal 1264 and a first electrode leading-out terminal 1266 are arranged on the second electrode layer 126, the first electrode layer 122 is led out by forming a through hole on the piezoelectric material layer 124, so that the electric connection with the first electrode 1222 on the first electrode layer 122 is easy, and the wiring on the side surface is not needed; the first electrode leading-out terminal 1266 is electrically connected with the first electrode 1222, the second electrode 1262 is electrically connected with the second electrode leading-out terminal 1264, so that an external signal processing circuit is directly and electrically connected with the first electrode leading-out terminal 1266 and the second electrode leading-out terminal 1264 which are positioned on the surface of the piezoelectric diaphragm 120, and the whole wiring is more regular; the piezoelectric diaphragm 120 further includes a flexible thin film layer 128 sequentially stacked between the support structure 110 and the first electrode layer 122, and the flexible thin film layer 128 is beneficial to driving the deformation of the piezoelectric material layer 124, so as to improve the signal-to-noise ratio of the piezoelectric electroacoustic transducer.

It is understood that the dimensions of all of the figures in this application are not to scale and are merely schematic representations.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above 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.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the 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 patent shall be subject to the appended claims.

Claims

1. A piezoelectric transducer is characterized by comprising a supporting structure and a piezoelectric diaphragm arranged on the supporting structure; the piezoelectric diaphragm comprises at least two adjacent diaphragms, and a gap is formed between the two adjacent diaphragms; the fixed edge of the diaphragm is supported by the supporting structure, and the part of the diaphragm which is not fixed is a free end;

2. The piezoelectric transducer of claim 1, wherein the fixed edges of two adjacent membranes form an included angle therebetween, the included angle being greater than 0 degrees and less than 180 degrees.

3. The piezoelectric transducer of claim 2, wherein the fixed edges of two adjacent diaphragms are perpendicular to each other.

4. The piezoelectric transducer of claim 2, wherein the number of membranes is four, and four membranes are arranged in two rows and two columns.

5. The piezoelectric transducer of claim 1, wherein the support structure includes a substrate and a sacrificial layer disposed on the substrate, the sacrificial layer being disposed adjacent to the piezoelectric diaphragm;

6. The piezoelectric transducer of claim 5, wherein the back cavity is square in cross-section and the diaphragm is a rectangular diaphragm.

7. The piezoelectric transducer of claim 1, wherein the free ends of the membranes are identical in shape and area.

8. The piezoelectric transducer of claim 1, wherein the piezoelectric diaphragm includes a first electrode layer, a piezoelectric material layer, and a second electrode layer, which are sequentially stacked and disposed on the support structure; the piezoelectric material layer is provided with a through hole so as to lead out the first electrode layer;

9. The piezoelectric transducer of claim 8, wherein the piezoelectric diaphragm further includes a flexible thin film layer and/or an insulating layer sequentially stacked and disposed between the support structure and the first electrode layer.

10. A method of making a piezoelectric transducer, the method comprising:

providing a support structure;

forming a piezoelectric diaphragm on the support structure;

11. The method of manufacturing a piezoelectric transducer as claimed in claim 10, wherein the step of opening a slit in the piezoelectric diaphragm opposite the back cavity is:

12. An electronic device, characterized in that the electronic device comprises a piezoelectric transducer as claimed in any one of claims 1 to 9.