CN116828367A

CN116828367A - Electrical control method for acoustic transducer, acoustic transducer and manufacturing method

Info

Publication number: CN116828367A
Application number: CN202310754113.XA
Authority: CN
Inventors: 易拥洁; 曾怀望
Original assignee: United Microelectronics Center Co Ltd
Current assignee: United Microelectronics Center Co Ltd
Priority date: 2023-06-25
Filing date: 2023-06-25
Publication date: 2023-09-29
Also published as: CN116828367A8

Abstract

An electrical modulation method for an acoustic transducer, and a method of manufacturing the same are provided. The acoustic transducer includes a membrane structure including a bottom electrode, a first piezoelectric layer disposed on the bottom electrode, and a first electrode layer disposed on the first piezoelectric layer, the method comprising: collecting, by a first one of the first center electrode and the first edge electrode, a first sensing electrical signal generated by means of a piezoelectric effect of the first piezoelectric layer when the acoustic transducer operates as an acoustic sensor, or applying a first control electrical signal to the first one when the acoustic transducer operates as an acoustic actuator, applying a first force to the membrane structure; and applying a first conditioning electrical signal to a second one of the first center electrode and the first edge electrode, applying a second force to the thin film structure.

Description

Electrical control method for acoustic transducer, acoustic transducer and manufacturing method

Technical Field

The present disclosure relates to the field of electronic technology, and in particular, to an electrical control method for an acoustic transducer, and a manufacturing method thereof.

Background

The acoustic transducer can realize acoustic-electric conversion and electric-acoustic conversion, and the membrane type piezoelectric acoustic transducer based on Micro-Electro-Mechanical System (MEMS) technology is stressed by researchers gradually due to the advantages of high sensitivity, low power consumption, miniaturization and the like of the piezoelectric membrane structure design, and is an important research direction of the acoustic sensor in the future in combination with the increasingly developed artificial intelligence technology.

Disclosure of Invention

It would be advantageous to provide a mechanism that alleviates, mitigates or even eliminates one or more of the above problems.

According to an aspect of the present disclosure, there is provided an electrical conditioning method for an acoustic transducer including a thin film structure including a bottom electrode, a first piezoelectric layer disposed on the bottom electrode, and a first electrode layer disposed on the first piezoelectric layer, the first electrode layer including a first center electrode and a first edge electrode electrically isolated from the first center electrode, the method including: collecting, by a first one of the first center electrode and the first edge electrode, a first sensing electrical signal generated by means of a piezoelectric effect of the first piezoelectric layer when the acoustic transducer operates as an acoustic sensor, or applying a first control electrical signal to the first one to apply a first force to the membrane structure by means of an electric field between the first one and the bottom electrode and an inverse piezoelectric effect of the first piezoelectric layer when the acoustic transducer operates as an acoustic actuator; and applying a first conditioning electrical signal to a second one of the first center electrode and the first edge electrode to apply a second force to the membrane structure by means of an electric field between the second one and the bottom electrode and an inverse piezoelectric effect of the first piezoelectric layer, wherein the second force conditions deformation of the membrane structure under external acoustic pressure when the acoustic transducer operates as an acoustic sensor, and wherein the second force conditions deformation of the membrane structure under the first force when the acoustic transducer operates as an acoustic actuator.

According to an aspect of the present disclosure, there is provided an acoustic transducer, a bottom electrode; the first piezoelectric layer is arranged on the bottom electrode; and a first electrode layer disposed on the first piezoelectric layer, the first electrode layer including a first center electrode and a first edge electrode electrically isolated from the first center electrode, the first center electrode being located at a center region of the thin film structure, the first edge electrode being located at a peripheral region of the thin film structure other than the center region, the first edge electrode including a plurality of first edge electrode blocks spaced apart from each other, wherein a first one of the first center electrode and the first edge electrode is configured to: i) Collecting a first sensing electrical signal generated by means of the piezoelectric effect of the first piezoelectric layer while the acoustic transducer is operating as an acoustic sensor; or ii) when the acoustic transducer is operated as an acoustic actuator, a first control electrical signal is applied to apply a first force to the membrane structure by means of an electric field between the first one and the bottom electrode and an inverse piezoelectric effect of the first piezoelectric layer, and wherein a second one of the first center electrode and the first edge electrode is configured to: a first conditioning electrical signal is applied to apply a second force to the membrane structure by means of an electric field between the second electrode and the bottom electrode and an inverse piezoelectric effect of the first piezoelectric layer, wherein the second force conditions deformation of the membrane structure under external acoustic pressure when the acoustic transducer operates as an acoustic sensor and conditions deformation of the membrane structure under the first force when the acoustic transducer operates as an acoustic actuator.

According to another aspect of the present disclosure, there is provided a method of manufacturing an acoustic transducer, comprising: providing a substrate; sequentially forming a bottom electrode, a first piezoelectric layer, and a first electrode layer stacked one on another on a substrate to obtain a thin film structure, the first electrode layer including a first center electrode and a first edge electrode electrically isolated from the first center electrode, the first center electrode being located at a center region of the thin film structure, the first edge electrode being located at a peripheral region of the thin film structure other than the center region, the first edge electrode including a plurality of first edge electrode blocks spaced apart from one another, wherein a first one of the first center electrode and the first edge electrode is configured to: i) Collecting a first sensing electrical signal generated by means of the piezoelectric effect of the first piezoelectric layer while the acoustic transducer is operating as an acoustic sensor; or ii) when the acoustic transducer is operated as an acoustic actuator, a first control electrical signal is applied to apply a first force to the membrane structure by means of an electrical field between the first and bottom electrodes and an inverse piezoelectric effect of the first piezoelectric layer, and wherein a second of the first center electrode and the first edge electrode is configured to apply a first tuning electrical signal to apply a second force to the membrane structure by means of an electrical field between the second and bottom electrodes and an inverse piezoelectric effect of the first piezoelectric layer, wherein the second force adjusts a deformation of the membrane structure under an external acoustic pressure when the acoustic transducer is operated as an acoustic sensor, and the second force adjusts a deformation of the membrane structure under the first force when the acoustic transducer is operated as an acoustic actuator.

These and other aspects of the disclosure will be apparent from and elucidated with reference to the embodiments described hereinafter.

Drawings

Further details, features and advantages of the present disclosure are disclosed in the following description of exemplary embodiments, with reference to the following drawings, wherein:

FIG. 1 is a schematic cross-sectional structure of an acoustic transducer according to an exemplary embodiment of the present disclosure;

FIG. 2 is a schematic top view of an acoustic transducer according to an exemplary embodiment of the present disclosure;

FIG. 3 is a schematic cross-sectional structure of an acoustic transducer according to another exemplary embodiment of the present disclosure;

FIG. 4 is a schematic cross-sectional structure of an acoustic transducer according to yet another exemplary embodiment of the present disclosure;

FIG. 5 is a schematic top view of an acoustic transducer according to another exemplary embodiment of the present disclosure;

fig. 6 to 10 are schematic cross-sectional structures of acoustic transducers according to exemplary embodiments of the present disclosure;

FIG. 11 is a simulated verification diagram for an acoustic transducer displacement and pressure distribution scenario;

FIG. 12 is a simulated verification graph for acoustic transducer displacement and stress distribution;

FIG. 13 is a flow diagram of an electrical conditioning method for an acoustic transducer according to an exemplary embodiment of the present disclosure;

FIG. 14 is a flow diagram of an electrical conditioning method for an acoustic transducer according to another exemplary embodiment of the present disclosure;

FIG. 15 is a flow diagram of an electrical conditioning method for an acoustic transducer according to yet another exemplary embodiment of the present disclosure;

FIG. 16 is a flow diagram of an electrical conditioning method for an acoustic transducer according to yet another exemplary embodiment of the present disclosure; and

fig. 17 is a schematic flow chart of a method of manufacturing an acoustic transducer according to an exemplary embodiment of the present disclosure.

Symbol description:

110-substrate, 111-first cavity, 120-bottom electrode, 121-center bottom electrode, 122-edge bottom electrode, 130-first piezoelectric layer, 140-first electrode layer, 141-first center electrode, 142-first edge electrode, 142 a-first edge electrode block, 150-additional piezoelectric layer, 160-additional electrode layer, 161-additional edge electrode, 162-additional center electrode.

Detailed Description

It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present disclosure.

Spatially relative terms, such as "under …," "under …," "lower," "under …," "above …," "upper," "top," "bottom," and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that these spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "under" or "beneath" other elements or features would then be oriented "over" the other elements or features. Thus, the exemplary terms "below …" and "below …" may encompass both orientations above … and below …. Terms such as "before …" or "before …" and "after …" or "followed by" may similarly be used, for example, to indicate the order in which light passes through the elements. The device may be oriented in other ways (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. In addition, it will also be understood that when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items, and the phrase "at least one of a and B" means a alone, B alone, or both a and B.

It will be understood that when an element or layer is referred to as being "on," "connected to," "coupled to," or "adjacent to" another element or layer, it can be directly on, connected to, coupled to, or adjacent to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly connected to," "directly coupled to," or "directly adjacent to" another element or layer, there are no intervening elements or layers present. However, in no event "on …" or "directly on …" should be construed as requiring one layer to completely cover an underlying layer.

Embodiments of the present disclosure are described herein with reference to schematic illustrations (and intermediate structures) of idealized embodiments of the present disclosure. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments of the present disclosure should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of the present disclosure.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and/or the present specification and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

As used herein, the term "substrate" may refer to a substrate of a diced wafer, or may refer to a substrate of an uncut wafer. Similarly, the terms chip and die (die) may be used interchangeably unless such interchange would cause a conflict. It should be understood that the term "layer" includes films and should not be construed to indicate vertical or horizontal thickness unless otherwise indicated.

There are two significant challenges in the operation of acoustic transducers: (1) The external pressure and the film stress deform the film structure of the acoustic transducer, so that the sensitivity, the dynamic range, the integral mechanical strength and the like of the acoustic transducer are influenced; (2) Excessive static/dynamic pressure and excessive film stress can cause damage to the film structure, which in turn can lead to device failure.

Therefore, it is important to enhance the sound pressure resistance of the device and to reduce or cancel the film stress of the device.

The larger the deformation of the thin film structure of the piezoelectric acoustic transducer, the larger the generated electrical signal, the smaller (thinner) the ratio of the thickness and the radius of the thin film structure, and the larger the output signal, the higher the device sensitivity. But the smaller the ratio of thickness to radius of the thin film structure (thinner) is more susceptible to damage, the smaller the withstand voltage capability and dynamic range of the device is. How to improve the pressure resistance and dynamic range of a device while ensuring that the sensitivity of a transducer is not reduced is a technical problem solved by the present disclosure.

According to one aspect of the present disclosure, there is provided an acoustic transducer in which a membrane structure is configured to apply a first conditioning electrical signal and a second force to the membrane structure. The second force may regulate and resist deformation of the external acoustic pressure or internal stress. And further enhances the pressure resistance of the acoustic transducer, expands the dynamic measurement range of the acoustic transducer, and ensures that the sensitivity (the radius ratio of the same thickness) of the acoustic transducer is not affected.

Fig. 1 is a schematic cross-sectional structure of an acoustic transducer according to an exemplary embodiment of the present disclosure. Fig. 2 is a schematic top view of an acoustic transducer according to an exemplary embodiment of the present disclosure.

As shown in fig. 1, the acoustic transducer includes a thin film structure including a substrate 110, a bottom electrode 120, a first piezoelectric layer 130, and a first electrode layer 140. Wherein the bottom electrode 120 is disposed on the substrate 110. The first piezoelectric layer 130 is disposed on the bottom electrode 120. The first electrode layer 140 is disposed on the first piezoelectric layer 130.

The first electrode layer 140 includes a first center electrode 141 and a first edge electrode 142 electrically isolated from the first center electrode 141. As shown in connection with fig. 2, the first center electrode 141 is located in the center region of the thin film structure. The first edge electrode 142 is located at a peripheral region of the thin film structure except for the central region. The first edge electrode 142 includes a plurality of first edge electrode blocks 142a spaced apart from each other.

The first one of the first center electrode 141 and the first edge electrode 142 is configured as i) or ii).

i) When the acoustic transducer operates as an acoustic sensor, a first sensing electrical signal generated by means of the piezoelectric effect of the first piezoelectric layer 130 is acquired.

Specifically, the first piezoelectric layer 130 is deformed to generate a first sensing electric signal when acted on by an external sound pressure.

ii) when the acoustic transducer is operated as an acoustic actuator, a first control electrical signal is applied to apply a first force to the membrane structure by means of an electric field between the first one and the bottom electrode 120 and the inverse piezoelectric effect of the first piezoelectric layer 130.

Specifically, when the first control electric signal is applied to the first piezoelectric layer, the stress is generated by the first piezoelectric layer 130 under the action of the electric field due to the inverse piezoelectric effect, so that the whole thin film structure is deformed.

The second of the first center electrode 141 and the first edge electrode 142 is configured to be applied with a first conditioning electrical signal to apply a second force to the thin film structure by means of an electric field between the second and bottom electrodes 120 and the inverse piezoelectric effect of the first piezoelectric layer 130. The second force adjusts the deformation of the membrane structure under external sound pressure when the acoustic transducer operates as an acoustic sensor, and the second force adjusts the deformation of the membrane structure under the first force when the acoustic transducer operates as an acoustic actuator.

Specifically, when the first adjusting electric signal is applied to the second electrode, the first piezoelectric layer 130 deforms under the action of the electric field to generate stress, and the stress generates a second acting force for deforming the thin film structure.

In the first case, the first center electrode 141 is the first one and the first edge electrode 142 is the second one. In the second case, the first edge electrode 142 is the first one and the first center electrode 141 is the second one. In the first case, the first edge electrode 142 as the first one includes a plurality of first edge electrode blocks 142a spaced apart from each other, so that the adjustment electric signal applied to the plurality of first edge electrode blocks 142a can be controlled to cause the set deformation of the thin film structure, and the adjustment manner in the first case is richer and the adjustment control fineness is higher than that in the second case (the whole structure) of the first edge electrode 142 as the first one.

In one embodiment, when the plurality of first edge electrode blocks 142a of the first edge electrode 142 are applied with the same-sized signal, the first edge electrode 142 may be used as a monolithic electrode.

According to the acoustic transducer of the embodiment of the present disclosure, the roles of the first center electrode 141 and the first edge electrode 142 can be interchanged, with great flexibility in use. In addition, the acoustic transducer can implement a dual electrode differential input/output function.

In one embodiment, the acoustic transducer further comprises a substrate 110. A substrate 110 is disposed below the thin film structure.

In one embodiment, the acoustic transducer further comprises a first cavity. The first cavity is disposed above or below the substrate 110. The first cavity is a closed cavity or an open cavity. For example, fig. 1 shows a case where the first cavity 111 is disposed under the substrate 110.

Further, the acoustic transducer further comprises a second cavity. The second cavity is opposite the first cavity with respect to the substrate 110. The second cavity is a closed cavity or an open cavity. The first cavity and/or the second cavity are configured to propagate an acoustic signal.

In some embodiments, as shown in fig. 1, the bottom electrode 120 is a monolithic structure.

The acoustic transducer provided in this embodiment can control the first adjusting electric signal applied to the second one of the first center electrode 141 and the first edge electrode 142 to make the membrane structure generate a set deformation for balancing the external pressure and the membrane stress, so that the membrane structure is in an optimal working state, and the signal acquisition or output is realized through the first one of the first center electrode 141 and the first edge electrode 142.

Fig. 3 is a schematic cross-sectional structure of an acoustic transducer according to another exemplary embodiment of the present disclosure. Like reference numerals in fig. 3 and 1 denote like elements, and are not repeated here.

As shown in fig. 3, the bottom electrode 120 includes a center bottom electrode 121 and an edge bottom electrode 122 electrically isolated from the center bottom electrode 121. The gap between the center bottom electrode 121 and the edge bottom electrode 122 is provided with a filler 123. The central bottom electrode 121 is located in the central region of the membrane structure. The edge bottom electrode 122 is located at the peripheral region of the thin film structure. The top view structure of the edge bottom electrode 122 is similar to the first edge electrode 142 in fig. 2, and the edge bottom electrode 122 includes a plurality of edge bottom electrode blocks spaced apart from each other.

The central bottom electrode 121 is configured as i) or ii).

i) When the acoustic transducer operates as an acoustic sensor and the first center electrode collects the first sensing electrical signal, a conductive path is formed with the first center electrode and the first piezoelectric layer.

ii) when the acoustic transducer is operated as an acoustic actuator and the first center electrode is applied with a first control electrical signal, an electric field is formed together with the first center electrode.

The edge bottom electrode is configured to be configured as i) or ii).

i) When the acoustic transducer operates as an acoustic sensor and the first edge electrode collects the first sensing electrical signal, a conductive path is formed with the first edge electrode and the first piezoelectric layer.

ii) when the acoustic transducer is operated as an acoustic actuator and the first edge electrode is applied with a first control electrical signal, an electric field is formed together with the first edge electrode.

In some embodiments, the central bottom electrode 121 may be used in conjunction with the first central electrode 141. The edge bottom electrode 122 and the first edge electrode 142 are used cooperatively.

In some embodiments, at least two of the center bottom electrode 121, the edge bottom electrode 122, the first center electrode 141, and the first edge electrode 142 are cooperatively acquired or applied with a signal. Thus, a plurality of matching modes can be formed to realize different control modes.

In some embodiments, at least two of at least one of the edge bottom electrode 122, at least one of the first edge electrode block 142a of the first edge electrode 142, the center bottom electrode 121, and the first center electrode 141 are cooperatively acquired or applied with signals. Thus, a plurality of matching modes can be formed to realize different control modes.

The acoustic transducer provided in this embodiment may have the edge bottom electrode 122 including a plurality of edge bottom electrode blocks and the first edge electrode 142 including a plurality of first edge electrode blocks 142a disposed at the upper and lower ends of the first piezoelectric layer 130, respectively. Thus, when the first edge electrode 142 is used as the second electrode, the adjusting electric signal can be applied by controlling different combinations of the plurality of edge bottom electrode blocks/the plurality of edge bottom electrode blocks, so that the whole thin film structure is subjected to preset deformation, and the signal acquisition or output is realized through the first central electrode 141. The embodiment can realize higher external pressure and film stress balance capability, and enhances the process fault tolerance, the disturbance rejection capability and the severe environment adaptability of the device.

In one embodiment, at least one additional piezoelectric layer 150 and at least one additional electrode layer 160 are also included in the acoustic transducer. At least one additional piezoelectric layer 150 and at least one additional electrode layer 160 are located above the first electrode layer 140 and are alternately stacked in a direction away from the substrate 110. At least one of the at least one additional electrode layer 160 includes an additional center electrode 162 and an additional edge electrode 161 electrically isolated from the additional center electrode. The additional center electrode 162 is located in the center region of the thin film structure. The additional edge electrode 161 is located at a peripheral region of the thin film structure. The top view structure of the additional piezoelectric layer 150 is similar to the first edge electrode 142 in fig. 2, and the additional edge electrode 161 includes a plurality of additional edge electrode blocks spaced apart from each other. For example, the acoustic transducer shown in fig. 4 includes two additional piezoelectric layers 150 and two additional electrode layers 160. Two additional piezoelectric layers 150 and two additional electrode layers 160 are alternately stacked over the first electrode layer 140.

The acoustic transducer provided in this embodiment may have an edge bottom electrode 122 including a plurality of edge bottom electrode blocks, a first edge electrode 142 including a plurality of first edge electrode blocks 142a, and at least one additional edge electrode 161 including a plurality of additional edge electrode blocks disposed at upper and lower ends of the first piezoelectric layer 130, respectively. Thus, when the first edge electrode 142 is used as the second electrode, the substrate 110 is subjected to the preset deformation as a whole by controlling different combinations of the plurality of edge bottom electrode blocks/the plurality of additional edge electrode blocks to apply the adjusting electric signals, and the signal acquisition or output is realized through the first center electrode 141. This embodiment may enable the ability to balance the effects of vector external pressure, uneven film stress, etc.

Fig. 5 is a schematic top view of an acoustic transducer according to another exemplary embodiment of the present disclosure. In comparison with fig. 2, the plurality of first edge electrode blocks 142a in fig. 2 have the same geometric parameters.

At least two first edge electrode blocks 142a among the plurality of first edge electrode blocks 142a in fig. 5 have different geometric parameters from each other. For example, the plurality of first edge electrode blocks 142a have different geometric parameters from each other. For another example, two first edge electrode blocks 142a among the plurality of first edge electrode blocks 142a have different geometric parameters from each other, and the other first edge electrode blocks 142a have the same geometric parameters from each other.

The geometric parameters may be, for example, length, width, diameter, area, shape, etc. In addition, the number of the first edge electrode blocks 142a may be changed by setting the geometric parameters of the first edge electrode blocks 142 a. For example, the greater the number of first edge electrode blocks 142a, the more precise control can be achieved from the standpoint of controlling the deformation by applying the adjustment electric signal.

It will be appreciated that in some embodiments, the schematic top view of the acoustic transducer described above with respect to fig. 1, 3, 4 may be as shown in fig. 2 or 5. For example, a schematic top view of the electrode layer in the acoustic transducer of fig. 1 may be as shown in fig. 2 or fig. 5. The schematic top view of the electrode layer in the acoustic transducer of fig. 3 may be as shown in fig. 2 or fig. 5. The schematic top view of the electrode layer in the acoustic transducer of fig. 3 may be as shown in fig. 2 or fig. 5. Fig. 1, 3 and 4 may be schematic cross-sectional structures taken along line AA in fig. 2 or 5.

Fig. 6-10 are schematic cross-sectional structural views of acoustic transducers according to exemplary embodiments of the present disclosure.

In one embodiment, fig. 6-7 may be represented as schematic cross-sectional structural views of an acoustic transducer under external acoustic pressure or first force. For example, as shown in fig. 6, the acoustic transducer is deformed to a first degree at a first pressure value at an external acoustic pressure or first force. For example, as shown in fig. 7, the acoustic transducer is deformed to a second degree at a second pressure value (e.g., twice the first pressure value) at an external acoustic pressure or first force.

In some embodiments, the membrane structure is controllably deformed relative to the baseline state at the second force to constrain the magnitude and/or direction of deformation of the membrane structure at the external acoustic pressure or the first force. The baseline state is a state of the thin film structure with the acoustic transducer in a non-operational state.

In some embodiments, the controlled deformation comprises one of: the thin film structure is convex, the thin film structure is concave, a first region of the thin film structure is convex and a second region of the thin film structure is concave.

In some embodiments, fig. 8 may be represented as a situation where the acoustic transducer is electrically controlled (with a conditioning electrical signal applied) in advance so that the membrane structure is pre-deformed (the membrane structure is raised) without being exposed to external sound pressure or a first force. According to the embodiment, the film structure is subjected to pre-deformation through advanced electrical regulation and control, so that deformation of the acoustic transducer due to external pressure or stress is resisted in the subsequent working process, the pressure resistance of the acoustic transducer is further enhanced, the dynamic measurement range of the acoustic transducer is expanded, and meanwhile, the sensitivity of the transducer is not influenced.

In some embodiments, fig. 6 may also be represented as a case where the acoustic transducer is electrically controlled (with an electrical conditioning signal applied) under an external acoustic pressure or a first force such that the membrane structure is controllably deformed relative to a baseline state to constrain the magnitude and/or direction of deformation of the membrane structure under the external acoustic pressure or the first force. Specifically, first, the acoustic transducer is deformed to a second extent at a second pressure value under an external sound pressure or a first acting force (see fig. 7). Then electronically controlled adjustment is performed, and an adjustment electrical signal is applied that can be used to balance the deformation such that the membrane structure undergoes a controlled deformation relative to the baseline state shown in fig. 7 to constrain the magnitude and/or direction of deformation of the membrane structure at external acoustic pressure or first force, assuming the configuration of fig. 6. The embodiment can enable the thin film structure to deform through electrical regulation and control so as to resist deformation of the acoustic transducer due to external pressure or stress, further enhance the pressure resistance of the acoustic transducer, expand the dynamic measurement range of the acoustic transducer and ensure that the sensitivity of the acoustic transducer is not affected.

In some embodiments, fig. 1 may also be represented as another case where the acoustic transducer is electrically controlled (with an electrical conditioning signal applied) under an external acoustic pressure or a first force such that the membrane structure is controllably deformed relative to a baseline state to constrain the magnitude and/or direction of deformation of the membrane structure under the external acoustic pressure or the first force. Specifically, first, the acoustic transducer is deformed to a first extent at a first pressure value under an external sound pressure or a first acting force (see fig. 6). Then electronically controlled adjustment is performed, and an adjustment electrical signal is applied that can be used to balance the deformation such that the membrane structure undergoes a controlled deformation relative to the baseline state shown in fig. 6 to constrain the magnitude and/or direction of deformation of the membrane structure at external acoustic pressure or first force, assuming the configuration of fig. 1. The embodiment can deform the substrate 110 through electrical regulation and control so as to resist deformation of the acoustic transducer due to external pressure or stress, further enhance the pressure resistance of the acoustic transducer, expand the dynamic measurement range of the acoustic transducer and ensure that the sensitivity of the acoustic transducer is not affected.

In some embodiments, fig. 9 and 10 may represent vector electronically controlled (with different conditioning electrical signals applied to deform the membrane structure in a particular direction) for the acoustic transducer, such that the substrate 110 deforms in a particular direction. This embodiment may enable a specific sensitivity to acoustic signals in a specific direction in space, i.e. to acoustic signals in a specific direction than to acoustic signals in other directions, with respect to the situation where the same sensitivity to acoustic signals in all directions is achieved. The embodiment can further enhance the regulation capability and the regulation precision of the device.

For acoustic transducers, there is a pressure to fail the structure, i.e., the deformation of the membrane structure caused by the pressure, and the deformation of the membrane structure can be described by the displacement of the center point of the membrane structure. First, the dynamic range is defined as + -100 Pa assuming that the initial state of the thin film structure is maximally subjected to 100Pa, i.e., that the displacement of the center point of the thin film structure is greater than 33nm, and that irreversible plastic deformation (failure of the thin film structure) occurs. Second, by controlling the conditioning electrical signal on the conditioning electrode (either the first center electrode or the first edge electrode), the static pressure bearing capacity of the membrane structure can be increased without failure deformation of the membrane structure, and the dynamic range of the transducer can be effectively increased. And thirdly, the excessive static pressure to which the film structure is subjected can be timely detected, and the film structure is protected from being damaged due to the excessive pressure by changing the electric signal on the regulating electrode.

Fig. 11 is a simulated verification diagram for the acoustic transducer displacement and pressure distribution case. As shown in fig. 11, it was found through simulation verification that: the voltage endurance capacity can be improved by +/-30 Pa (30%) and the dynamic range can be increased by 30% by performing electrical regulation in the regulating voltage range of +/-50V. The voltage endurance capacity is improved by +/-65 Pa (65%) and the dynamic range is increased by 65% by performing electrical regulation in a regulating voltage range of +/-100V.

For a thin film acoustic transducer, the deformation and failure of the thin film structure caused by excessive stress in the thin film structure can also have a certain influence on the sensitivity of the transducer. Deformation failure of the membrane structure can also be described by displacement of the membrane structure center point. First, excessive internal stress in the film can lead to deformation failure of the film structure, assuming 33nm is the limit for deformation failure of the film structure. Second, the internal stress of the membrane also inhibits deformation (displacement) of the membrane structure under external pressure, affecting the transducer sensitivity and reducing its dynamic range. Third, by controlling the conditioning electrical signal on the conditioning electrode (first center electrode or first edge electrode), the deformation due to the internal stress of the thin film can be balanced to some extent, reducing the effect of the stress. Fourth, can increase the mechanical reliability of the energy converter through the electric regulation mode, the device preparation technology is simpler, stability is high, reliability is good.

Fig. 12 is a simulated verification graph for acoustic transducer displacement and stress distribution. As shown in fig. 12, it was found through simulation verification that: electrical regulation over a regulated voltage range of + -50V can improve stress resistance by + -20 MN/m2 (about 28.57%). Electrical regulation over a regulated voltage range of + -100V can increase stress resistance by +40MN/m2 (about 57.14%).

The present disclosure provides an electrical regulation method for an acoustic transducer. The acoustic transducer may be any of the acoustic transducers described above. As shown in fig. 13, the electrical conditioning method 1300 includes the following steps 1310 and 1320.

In step 1310, a first sensing electrical signal generated by the piezoelectric effect of the first piezoelectric layer is acquired by a first one of the first center electrode and the first edge electrode when the acoustic transducer is operated as an acoustic sensor, or a first control electrical signal is applied to the first one to apply a first force to the membrane structure by means of an electric field between the first one and the bottom electrode and an inverse piezoelectric effect of the first piezoelectric layer when the acoustic transducer is operated as an acoustic actuator.

The specific operation of this step is substantially the same as the relevant operation that the first one of the first center electrode and the first edge electrode in the acoustic transducer is configured to perform, and will not be described herein.

In step 1320, a first conditioning electrical signal is applied to a second one of the first center electrode and the first edge electrode to apply a second force to the membrane structure by way of an electric field between the second one and the bottom electrode and an inverse piezoelectric effect of the first piezoelectric layer, wherein the second force conditions deformation of the membrane structure under external acoustic pressure when the acoustic transducer operates as an acoustic sensor. Wherein the second force adjusts the deformation of the membrane structure under the first force when the acoustic transducer is operated as an acoustic actuator.

The specific operation of this step is substantially the same as the relevant operation that the second one of the first center electrode and the first edge electrode is configured to perform in the above-described acoustic transducer, and will not be described herein.

In connection with fig. 1, 6 and 7, the deformation of the thin film structure without electrical control can be shown. Specifically, the thin film structure assumes the state shown in fig. 1 without external sound pressure and without electrical regulation. When the applied external sound pressure is a first pressure value and without electrical regulation, the thin film structure exhibits the degree of deformation shown in fig. 6. In the case where the applied external sound pressure is a second pressure value (e.g., twice the first pressure value) and no electrical regulation is performed, the thin film structure exhibits the degree of deformation shown in fig. 7. It can be seen from this that, without electrical regulation, different degrees of deformation occur under different external acoustic pressures. The greater the external sound pressure, the greater the degree of deformation of the membrane structure, which in turn can lead to damage to the membrane structure.

In connection with fig. 8, 1 and 6, the deformation of the thin film structure under pre-electric control can be shown. Specifically, the thin film structure exhibits the pre-deformation shown in fig. 8 without external sound pressure and pre-electric regulation. In the case of pre-electrically regulated, applied external sound pressure at a first pressure value, the membrane structure assumes the state shown in fig. 1. In the case of pre-electrically regulated, applied external sound pressure at the second pressure value, the membrane structure assumes the state shown in fig. 6. Therefore, the film structure is pre-deformed by conducting electrical regulation in advance, deformation of the film structure due to external pressure or stress can be resisted and balanced, and pressure resistance of the acoustic transducer is further improved.

Further, the workflow of the pre-electricity regulation will be described with reference to fig. 13. In a first step, an initial static pressure value is known and a preliminary electrical conditioning operation is performed in an attempt to reach the desired equilibrium state of the membrane structure of the acoustic transducer. And secondly, judging whether the film structure is balanced or not. If the pressure is judged to be in the balance state, the pressure is detected. If the film structure is judged not to be in the balance state, the effect of the pre-electricity regulation is insufficient to bring the film structure into the balance state, and the second step is continued after the pre-electricity regulation degree is enhanced.

Through the circulation of pre-electric regulation and control and balance state judgment, the acoustic transducer gradually approaches to the required balance state through continuous regulation and judgment.

In connection with fig. 1 and 6, the deformation of the thin film structure under electrical control can be represented. Specifically, the thin film structure assumes the state shown in fig. 1 without external sound pressure and without electrical regulation. When the applied external sound pressure is a first pressure value and without electrical regulation, the thin film structure exhibits the degree of deformation shown in fig. 6. In the case where the applied external sound pressure is the second pressure value and is electrically controlled, the thin film structure exhibits the degree of deformation shown in fig. 1. Therefore, in the process of applying external sound pressure to the film structure, the film structure is electrically regulated and controlled, and deformation generated in the process of applying external sound pressure to the film structure can be resisted and balanced under the action of the electrical regulation and control, so that the deformation degree of the film structure is reduced.

Further, the workflow of the electrical control will be described with reference to fig. 14. In a first step, a pressure change is detected. And a second step of judging whether the film structure is subjected to excessive deformation. A sensor or other measuring device may be used to monitor the degree of deformation of the thin film structure and compare it to a set threshold. Excessive deformation may lead to cracking or damage of the thin film structure for electrical regulation.

The method is beneficial to maintaining the balanced working state of the acoustic transducer by monitoring the deformation of the thin film structure and performing corresponding electrical regulation.

In connection with fig. 1, 9 and 10, the deformation of the thin film structure under vector electrical control can be represented. Specifically, the thin film structure assumes the state shown in fig. 1 without external sound pressure and without electrical regulation. The membrane structure is subjected to different vector control, and the membrane structure is shown as deformation in a specific direction in fig. 9 or 10.

Further, the workflow of vector electrical control will be described in conjunction with fig. 15.

In a first step, a pressure change is detected. For example using a suitable sensor or measuring device to detect changes in pressure. And a second step of analyzing the detected pressure change data to determine whether it has directionality. Directionality may be manifested as a change in pressure in a particular direction, such as stretching, compression, or torsion. By analyzing the magnitude and direction of the pressure change, it can be determined whether or not directionality is present. And if the pressure is determined to have directivity, carrying out vector electric control adjustment. Different adjusting electric signals are applied, so that the thin film structure deforms in a specific direction.

The deformation direction of the film structure can be accurately controlled according to the directionality of pressure change through vector electric control adjustment.

Fig. 17 is a schematic flow chart of a method of manufacturing an acoustic transducer according to an exemplary embodiment of the present disclosure. As shown in fig. 17, the method includes:

at step 1710, a substrate is provided.

In some embodiments, the substrate may be made of a material that is predominantly silicon.

At 1720, a bottom electrode is formed on a substrate.

In some embodiments, the bottom electrode is a monolithic structure. The bottom electrode is made of conductive metal and alloy such as gold, silver, copper, molybdenum (Mo), platinum (Pt) and the like. The method of forming the bottom electrode includes, but is not limited to, sputter deposition and the like, and is not limited thereto.

At step 1730, a first piezoelectric layer is formed on the bottom electrode.

In some embodiments, the first piezoelectric layer is a piezoelectric material, such as aluminum nitride, zinc oxide, piezoelectric ceramic, or the like.

In some embodiments, the method of forming the first piezoelectric layer includes, but is not limited to, sputter deposition, and the like.

In step 1740, a first electrode layer is formed over the first piezoelectric layer. The first electrode layer includes a first center electrode and a first edge electrode electrically isolated from the first center electrode.

In some embodiments, the first center electrode, the first edge electrode, and the second electrode are made of an electrode material, such as gold, silver, or copper. The filler material is a dielectric material such as silicon dioxide.

Steps 1710-1740 are followed to obtain a thin film structure.

In some embodiments, a first cavity may be formed on a first side of the substrate. For example, the first cavity may be formed by a process such as bonding prior to step 1720. For another example, the first cavity may be etched in the substrate from bottom to top, such as by an etching process (e.g., bosch process), after step 1740.

In some embodiments, the second cavity is formed on an opposite side of the first side of the substrate.

In some embodiments, the substrate may be removed during step 1710 and step 1740 or after step 1740. The performance of the device with the substrate removed is advantageous in some aspects, such as sensitivity performance.

The first cavity and the second cavity are provided on both sides of the membrane structure to obtain an acoustic transducer as shown in fig. 1 or fig. 3, for example.

In some embodiments, the bottom electrode includes a center bottom electrode and an edge bottom electrode electrically isolated from the center bottom electrode. The bottom electrode may be formed as follows: first, a conductive layer is provided over a substrate. The conductive layer is patterned to form a center bottom electrode located in a center region of the thin film structure and an edge bottom electrode located in a peripheral region of the thin film structure other than the center region. And finally, filling the filling material in a gap between the central bottom electrode and the edge bottom electrode, wherein the central bottom electrode, the edge bottom electrode and the filling material jointly form the edge bottom electrode.

In some embodiments, the first electrode layer may be formed as follows: first, a conductive layer is provided on a first piezoelectric layer. The conductive layer is patterned to form a first center electrode located in a center region of the thin film structure and a first edge electrode located in a peripheral region of the thin film structure other than the center region. And finally, filling the filling material in the gap between the first central electrode and the first edge electrode, wherein the first central electrode, the first edge electrode and the filling material jointly form a first electrode layer.

In some embodiments, the method may further comprise: at least one additional piezoelectric layer and at least one additional electrode layer are alternately stacked on the first electrode layer. At least one of the at least one additional electrode layers includes an additional center electrode and an additional edge electrode electrically isolated from the additional center electrode. The material and formation method of the additional piezoelectric layer are similar to those of the first piezoelectric layer. Additional piezoelectric layer the structure and method of formation of the additional electrode layer is similar to that of the first electrode layer. An acoustic transducer such as that shown in fig. 4 can be obtained by this embodiment.

While the disclosure has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative and schematic and not restrictive; the present disclosure is not limited to the disclosed embodiments. Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed subject matter, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps than those listed and the indefinite article "a" or "an" does not exclude a plurality, and the term "plurality" means two or more. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

1. An electrical conditioning method for an acoustic transducer, the acoustic transducer comprising a thin film structure comprising a bottom electrode, a first piezoelectric layer disposed on the bottom electrode, and a first electrode layer disposed on the first piezoelectric layer, the first electrode layer comprising a first center electrode and a first edge electrode electrically isolated from the first center electrode, the method comprising:

collecting, by a first one of the first center electrode and the first edge electrode, a first sensing electrical signal generated by means of a piezoelectric effect of the first piezoelectric layer when the acoustic transducer is operated as an acoustic sensor, or applying a first control electrical signal to the first one when the acoustic transducer is operated as an acoustic actuator to apply a first force to the membrane structure by means of an electric field between the first one and the bottom electrode and an inverse piezoelectric effect of the first piezoelectric layer; and

applying a first conditioning electrical signal to a second one of said first center electrode and said first edge electrode to apply a second force to said thin film structure by means of an electric field between said second one and said bottom electrode and an inverse piezoelectric effect of said first piezoelectric layer,

Wherein the second force adjusts the deformation of the membrane structure under external acoustic pressure when the acoustic transducer operates as the acoustic sensor, an

Wherein the second force adjusts the deformation of the membrane structure under the first force when the acoustic transducer operates as the acoustic actuator.

2. The method of claim 1, wherein the bottom electrode is a monolithic structure.

3. The method of claim 1, wherein the bottom electrode comprises a central bottom electrode and an edge bottom electrode electrically isolated from the central bottom electrode, the central bottom electrode being located in the central region of the thin film structure, the edge bottom electrode being located in the peripheral region of the thin film structure, the edge bottom electrode comprising a plurality of edge bottom electrode blocks spaced apart from one another,

wherein the central bottom electrode is configured to: i) Forming a conductive path with the first center electrode and the first piezoelectric layer when the acoustic transducer operates as the acoustic sensor and the first center electrode collects the first sensing electrical signal; or ii) when the acoustic transducer is operated as the acoustic actuator and the first center electrode is applied with the first control electrical signal, the electric field is formed together with the first center electrode, and

Wherein the edge bottom electrode is configured to: i) Forming a conductive path with the first edge electrode and the first piezoelectric layer when the acoustic transducer operates as the acoustic sensor and the first edge electrode collects the first sensing electrical signal; or ii) forming the electric field together with the first edge electrode when the acoustic transducer is operated as the acoustic actuator and the first control electric signal is applied to the first edge electrode.

4. A method according to any of claims 1-3, wherein the acoustic transducer further comprises at least one additional piezoelectric layer and at least one additional electrode layer located above the first electrode layer and alternately stacked in a direction away from the first electrode layer, at least one of the at least one additional electrode layers comprising an additional center electrode located at the central region of the thin film structure and an additional edge electrode electrically isolated from the additional center electrode located at the peripheral region of the thin film structure, the additional edge electrode comprising a plurality of additional edge electrode blocks spaced apart from each other.

5. A method according to any of claims 1-3, wherein the plurality of first edge electrode blocks have the same geometrical parameters.

6. A method according to any of claims 1-3, wherein at least two first edge electrode blocks of the plurality of first edge electrode blocks have different geometrical parameters from each other.

7. A method according to any of claims 1-3, wherein the second force causes a controlled deformation of the membrane structure relative to a baseline state to constrain the magnitude and/or direction of deformation of the membrane structure at the external acoustic pressure or the first force, wherein the baseline state is a state of the membrane structure in a non-operational state of the acoustic transducer.

8. The method of claim 7, wherein the controlled deformation comprises one of: the thin film structure is convex, the thin film structure is concave, a first region of the thin film structure is convex, and a second region of the thin film structure is concave.

9. A method according to any of claims 1-3, wherein the acoustic transducer further comprises:

and the substrate is arranged below the film structure.

10. The method of claim 9, wherein the acoustic transducer further comprises:

the first cavity is arranged above or below the substrate and is a closed cavity or an open cavity.

11. The method of claim 9, wherein the acoustic transducer further comprises:

and a second cavity opposite to the first cavity with respect to the substrate, wherein the second cavity is a closed cavity or an open cavity.

12. An acoustic transducer comprising a membrane structure, the membrane structure comprising:

a bottom electrode;

a first piezoelectric layer disposed on the bottom electrode; and

a first electrode layer disposed on the first piezoelectric layer, the first electrode layer including a first center electrode and a first edge electrode electrically isolated from the first center electrode, the first center electrode being located at a center region of the thin film structure, the first edge electrode being located at a peripheral region of the thin film structure other than the center region, the first edge electrode including a plurality of first edge electrode blocks spaced apart from each other,

wherein a first one of the first center electrode and the first edge electrode is configured to: i) Acquiring a first sensing electrical signal generated by means of the piezoelectric effect of the first piezoelectric layer while the acoustic transducer is operating as an acoustic sensor; or ii) when the acoustic transducer is operated as an acoustic actuator, a first control electrical signal is applied to apply a first force to the membrane structure by means of an electric field between the first and bottom electrodes and an inverse piezoelectric effect of the first piezoelectric layer, and

Wherein a second one of the first center electrode and the first edge electrode is configured to: a first conditioning electrical signal is applied to apply a second force to the membrane structure by means of an electric field between the second and bottom electrodes and an inverse piezoelectric effect of the first piezoelectric layer, wherein the second force conditions deformation of the membrane structure under external acoustic pressure when the acoustic transducer operates as the acoustic sensor and conditions deformation of the membrane structure under the first force when the acoustic transducer operates as the acoustic actuator.

13. The acoustic transducer of claim 12, wherein the bottom electrode is of unitary construction.

14. The acoustic transducer of claim 12 wherein the bottom electrode comprises a central bottom electrode and an edge bottom electrode electrically isolated from the central bottom electrode, the central bottom electrode being located in the central region of the thin film structure, the edge bottom electrode being located in the peripheral region of the thin film structure, the edge bottom electrode comprising a plurality of edge bottom electrode blocks spaced apart from one another,

15. The acoustic transducer of any of claims 12-14, further comprising at least one additional piezoelectric layer and at least one additional electrode layer located above the first electrode layer and alternately stacked in a direction away from the first electrode layer, at least one of the at least one additional electrode layer comprising an additional center electrode located at the center region of the thin film structure and an additional edge electrode electrically isolated from the additional center electrode located at the peripheral region of the thin film structure, the additional edge electrode comprising a plurality of additional edge electrode blocks spaced apart from one another.

16. The acoustic transducer according to any of claims 12-14, wherein the plurality of first edge electrode blocks have the same geometric parameters.

17. The acoustic transducer of any of claims 12-14, wherein at least two first edge electrode blocks of the plurality of first edge electrode blocks have different geometric parameters from each other.

18. The acoustic transducer of any of claims 12-14, wherein the second force causes a controlled deformation of the thin film structure relative to a baseline state to constrain an amplitude and/or direction of deformation of the thin film structure at the external acoustic pressure or the first force, wherein the baseline state is a state of the thin film structure in a non-operational state of the acoustic transducer.

19. The acoustic transducer of claim 18, wherein the controlled deformation comprises one of: the thin film structure is convex, the thin film structure is concave, a first region of the thin film structure is convex, and a second region of the thin film structure is concave.

20. The acoustic transducer according to any of claims 12-14, further comprising:

and the substrate is arranged below the film structure.

21. The acoustic transducer of claim 20, further comprising:

22. The acoustic transducer of claim 20, further comprising:

23. A method of manufacturing an acoustic transducer, comprising:

providing a substrate;

sequentially forming a bottom electrode, a first piezoelectric layer and a first electrode layer stacked on each other on the substrate to obtain a thin film structure, the first electrode layer including a first center electrode and a first edge electrode electrically isolated from the first center electrode, the first center electrode being located at a center region of the thin film structure, the first edge electrode being located at a peripheral region of the thin film structure other than the center region, the first edge electrode including a plurality of first edge electrode blocks spaced apart from each other,

Wherein a second one of the first center electrode and the first edge electrode is configured to be applied with a first conditioning electrical signal to apply a second force to the membrane structure by means of an electrical field between the second one and the bottom electrode and an inverse piezoelectric effect of the first piezoelectric layer, wherein the second force conditions deformation of the membrane structure under external sound pressure when the acoustic transducer operates as the acoustic sensor and conditions deformation of the membrane structure under the first force when the acoustic transducer operates as the acoustic actuator.

24. The method of claim 23, wherein the bottom electrode is a monolithic structure.

25. The method of claim 23, wherein the bottom electrode comprises a central bottom electrode and an edge bottom electrode electrically isolated from the central bottom electrode, the central bottom electrode being located in the central region of the thin film structure, the edge bottom electrode being located in the peripheral region of the thin film structure, the edge bottom electrode comprising a plurality of edge bottom electrode blocks spaced apart from one another,

26. The method of any of claims 23-25, further comprising:

at least one additional piezoelectric layer and at least one additional electrode layer are alternately stacked on the first electrode layer, at least one of the at least one additional electrode layer including an additional center electrode and an additional edge electrode electrically isolated from the additional center electrode, the additional center electrode being located at the center region of the thin film structure, the additional edge electrode being located at the peripheral region of the thin film structure, the additional edge electrode including a plurality of additional edge electrode blocks spaced apart from each other.

27. The method of any of claims 23-25, further comprising:

And removing the substrate.