Microelectromechanical membrane transducer with active damper

Abstract

A microelectromechanical membrane transducer with an active damper is disclosed. The microelectromechanical membrane transducer includes: a support structure; a cavity in the support structure; a membrane coupled to the support structure to cover the cavity on one side; a cantilever damper fixed to the support structure around the perimeter of the membrane and extending towards the interior of the membrane at a distance from the membrane; and a damper piezoelectric actuator disposed on the cantilever damper and configured to bend the cantilever damper towards the membrane in response to an electroactuation signal.

Description

Technical Field

[0001] The present disclosure relates to microelectromechanical membrane transducers, methods for controlling microelectromechanical membrane transducers, and processes for manufacturing microelectromechanical membrane transducers. Background Art

[0002] It is known that microelectromechanical membrane transducers can be used in various fields for receiving and generating pressure waves. This type of microelectromechanical transducer can be used in a unidirectional manner (e.g., pressure sensors and microphones) or in a bidirectional manner, for example, to provide ultrasonic probes for various applications.

[0003] Microelectromechanical ultrasonic transducers generally include: a support structure of semiconductor material in which a cavity is formed; and a membrane that closes the cavity on one side, which is also of semiconductor material. A piezoelectric plate is formed on the membrane and connected to a drive device that alternately enables a drive signal to be applied to the piezoelectric plate for generating a pressure wave and for detecting the oscillation of the membrane caused by the echo of the transmitted pressure wave. In practice, the microelectromechanical transducer switches between a transmission mode and a reception mode. In the transmission mode, the drive device uses a burst of pulses to excite the piezoelectric plate and causes the membrane to vibrate, which generates a pressure wave of controlled amplitude and frequency. In the reception mode, the membrane is set into vibration by an echo caused by a change in the medium density along the propagation path of the pressure wave emitted in the transmission step. The piezoelectric plate converts the oscillation of the diaphragm into a transducer signal, which is detected and amplified by the drive device.

[0004] A common problem with microelectromechanical membrane transducers is the damping time of the oscillation of the membrane when switching between the transmission mode and the reception mode, especially in "air" applications.

[0005] When the microelectromechanical transducer switches to the reception mode, the membrane continues to vibrate (i.e., ring) and generates a tail of the pressure wave within a time determined by a damping factor, which is typically relatively low in order to obtain higher sensitivity. On the one hand, the tail of the pressure wave causes noise and may make the processing of the returned signal more complex. On the other hand, before the microelectromechanical transducer is ready to receive an echo in the reception mode, it is necessary to wait for the tail of the pressure wave to disappear. This has an impact on the depth of the blind zone that cannot be investigated, because the echo of a possible obstacle will be superimposed on the tail of the pressure wave.

[0006] Solutions have been proposed, however, these solutions are not satisfactory in the first place because they are too sensitive to variability in the manufacturing process.

[0007] For example, the detection of the oscillation of the active suppression assumption membrane and the application of the anti-phase drive signal are considered, and the filtering technique during post-processing aims to eliminate the influence of the tail downstream of the detected pressure wave. However, in both cases, the effectiveness of the correction action is thus related to the parameters of the individual microelectromechanical transducers and the environmental conditions, such that the non-removable expansion of the manufacturing process will force the calibration and testing of each individual element produced, resulting in unsustainable costs. Summary of the Invention

[0008] The present disclosure provides a microelectromechanical membrane transducer, a method for controlling a microelectromechanical membrane transducer, and a process for manufacturing a microelectromechanical membrane transducer, which overcome or mitigate the above limitations and the like. Brief Description of the Drawings

[0009] To better understand the present disclosure, some embodiments thereof will now be described only by way of non-limiting examples and with reference to the accompanying drawings, in which:

[0010] Figure 1 is a partial cross-sectional perspective view of a microelectromechanical membrane transducer according to an embodiment of the present disclosure.

[0011] Figure 2 is Figure 1 a cross-sectional view of the microelectromechanical membrane transducer shown.

[0012] Figure 3 is Figure 1 a top view of the microelectromechanical membrane transducer of Figure 2 taken along line III-III, with parts removed for clarity.

[0013] Figure 4 shows Figure 2 an enlarged detail;

[0014] Figure 5a is a graph showing a first quantity of the microelectromechanical membrane transducer with respect to Figure 1 under a first operating condition;

[0015] Figure 5b is a graph showing the first quantity under a second operating condition;

[0016] Figure 5c is a graph showing a second quantity of the microelectromechanical membrane transducer with respect to Figure 1 under a first operating condition;

[0017] Figure 5d is a graph showing the second quantity under a second operating condition;

[0018] Figure 6a is a graph showing a first control quantity used in the microelectromechanical membrane transducer of Figure 1 ;

[0019] Figure 6b is a diagram showing a second control quantity used in a microelectromechanical membrane transducer of Figure 1 .

[0020] Figure 7 is a top view of a microelectromechanical membrane transducer according to different embodiments of the present disclosure, where parts are removed for clarity;

[0021] Figure 8 is a top view of a microelectromechanical membrane transducer according to another embodiment of the present disclosure, where parts are removed for clarity;

[0022] Figure 9 is a top view of a microelectromechanical membrane transducer according to another embodiment of the present disclosure, where parts are removed for clarity; and

[0023] Figures 10 - 14 is a cross-sectional view of a semiconductor wafer in different processing steps of a process for manufacturing a microelectromechanical membrane transducer according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0024] Referring to Figure 1 , reference numeral 1 generally denotes a microelectromechanical membrane transducer according to an embodiment of the present disclosure. The microelectromechanical membrane transducer 1 includes: a support structure 2 in which a cavity 3 is formed; a membrane 5 coupled to the support structure 2 to cover the cavity 3 on one side; and a cantilever damper 7.

[0025] The microelectromechanical membrane transducer 1 further includes a membrane piezoelectric actuator 8, a damper piezoelectric actuator 10, and a driving device 12 coupled to the membrane piezoelectric actuator 8 and the damper piezoelectric actuator 10. In one embodiment (not shown), respective different driving circuits may be coupled to the membrane piezoelectric actuator 8 and the damper piezoelectric actuator 10.

[0026] The support structure 2 is obtained from a substrate of semiconductor material and has, as a non-limiting example, an annular shape. The cavity 3 extends through the entire support structure 2, being open on one side and covered by the membrane 5 on the other side.

[0027] The membrane 5 is connected to the support structure 2 along its perimeter, and in one embodiment, the membrane 5 is of semiconductor material and is circular. For example, the membrane 5 has a diameter between about 600 μm and about 800 μm and a thickness between about 0.5 μm and about 15 μm.

[0028] Opposite faces of the membrane 5 are coated with respective silicon oxide protective layers 13, 14. In Figure 1 and 2In the example, the membrane 5 is continuous and has a circular shape. However, in some embodiments (not shown), depending on the design preference, the membrane 5 may be perforated and have any shape.

[0029] In addition, the membrane piezoelectric actuator 8 is disposed at the center of the membrane 5 and includes a piezoelectric material plate between a first membrane electrode 16 and a second membrane electrode 17. The first membrane electrode 16 and the second membrane electrode 17 are coupled to the driving device 12 to alternately supply the membrane-actuating signal SM and receive the received signal SR. As a non-limiting example, the piezoelectric material may be PZT (lead zirconate titanate). The membrane 5, the membrane piezoelectric actuator 8, and the membrane electrodes 16, 17 are coated with a passivation layer, such as a multi-layer of USG (undoped silicate glass) 18 and silicon nitride 19.

[0030] The cantilever damper 7 includes an annular-shaped bracket 20 that is fixed to the support structure 2 around the periphery of the membrane 5 and extends inwardly toward the inside of the membrane 5 at a certain distance from the membrane 5. More precisely, the anchorage region 21 (from which the bracket 20 protrudes) is connected to the support structure 2 through an adhesive layer 23 around the membrane 5. The bracket 20 protrudes from the anchorage region 21 by an amount, for example, between about 100 μm and about 200 μm, and has a thickness between about 0.5 μm and about 5 μm. The stop element 25, which also has an annular shape, extends from the radially inner edge of the bracket 20 in the direction toward the membrane 5. In one embodiment, the anchorage region 21 and the stop element 25 have the same structure; for example, they are epitaxial silicon coated with silicon oxide on the side facing the diaphragm 5. When the membrane 5 is stationary and the damper piezoelectric actuator 10 is not activated, the stop element 25 is located at a distance, for example, about 1 μm from the membrane 5.

[0031] The damper piezoelectric actuator 10 includes a continuous annular region of piezoelectric material (such as PZT) that is disposed on the cantilever damper 7 along the inner peripheral edge of the cantilever damper 7, particularly on the face of the bracket 20 opposite to the membrane 5 and is included between a first damper electrode 26 and a second damper electrode 27. For example, the annular region of the piezoelectric material has a thickness between about 0.5 μm and about 3 μm (perpendicular to the membrane 5) and a width between about 80 μm and about 1000 μm (in the direction parallel to the membrane 5). In the illustrated case, where the annular region of the piezoelectric material has an annular shape, the width is the difference between the outer radius and the inner radius.

[0032] A passivation layer (such as a multi-layer of USG 28 and silicon nitride 29) covers the damper piezoelectric actuator 10, the damper electrodes 26, 27, and the rest of the bracket 20.

[0033] The damper piezoelectric actuator 10 is configured to bend the cantilever damper 7 (particularly the bracket 20) toward the membrane 5 in response to the damper actuation signal SD, asFigure 4 As shown. In one embodiment, the damper piezoelectric actuator 7 extends along the radially inner edge of the bracket 20. The bending of the bracket 20 causes the stop element 25 to contact the membrane 5 and actually causes an increase in the damping coefficient of the oscillation system. The activation of the damper piezoelectric actuator 7 thus reduces the time for suppressing the oscillation of the membrane.

[0034] Figures 5a - 5d A comparison between the behavior of the membrane 5 with and without the intervention of the damper piezoelectric actuator 7 is shown. More precisely, Figure 5a and Figure 5b show the oscillation amplitude of the membrane 5, while Figure 5c and Figure 5d show the pressure in the air at a reference distance from the plane of the stationary membrane 5. Figure 5a and Figure 5c The graphs of are obtained without activating the membrane piezoelectric actuator 7. Figure 5b and Figure 5d The graphs of are obtained with the membrane piezoelectric actuator 7 activated, and clearly show its effect in reducing the oscillation damping time.

[0035] The drive device 12 is configured to apply a membrane actuation signal SM to the membrane piezoelectric actuator 8 in the transmission mode, and receive and amplify the received signal SR generated by the membrane piezoelectric transducer 8 due to the oscillation of the membrane 5. The drive device 12 switches between the transmission mode and the reception mode. In the transmission mode, the membrane piezoelectric transducer 12 is used to transmit a pressure wave packet, and in the reception mode, the membrane piezoelectric transducer 8 is used to detect the echo generated due to the reflection of the pressure wave transmitted to an obstacle arranged along the propagation path.

[0036] In addition, the drive device 12 is configured to apply a damper actuation signal SD to the damper piezoelectric actuator 10. In response to the damper actuation signal SD, the damper piezoelectric actuator 10 causes the bending of the bracket 20, and the stop element 25 contacts the membrane 5 and causes faster damping of the oscillation.

[0037] The membrane actuation signal SM and the damper actuation signal SD can be synchronized, as indicated in Figure 6a and Figure 6b . In particular, the membrane actuation signal SM ( Figure 6a ) increases according to a ramp from the minimum membrane value VMINM to the maximum membrane value VMAXM, and after a settling interval, oscillates a plurality of programmed cycles between the minimum membrane value VMINM and the maximum membrane value VMAXM. The damper actuation signal SD ( Figure 6b)It increases according to a ramp from a minimum damper value VMIND to a maximum damper value VMAXD so that the stop element 25 gradually comes into contact with the membrane 5 immediately after a plurality of programmed cycles of the membrane actuation signal SM have been completed. In particular, the contact occurs before the end of the transient of the natural damping of the oscillations of the membrane 5 (i.e., without the intervention of the damper piezoelectric actuator 10). The start of the ramp is selected so that the contact between the stop element 25 and the membrane 5 occurs at the desired moment. When the transient of the damping of the oscillations of the membrane 5 ends, the damper actuation signal SD decreases according to a ramp from the maximum damper value VMAXD to the minimum damper value VMIND so as to gradually interrupt the contact between the stop element 25 and the membrane 5. The gradual contact (first) and the gradual separation (second) between the stop element 25 and the membrane 5 prevent the perturbation of the state of the membrane 5 itself, which is quickly ready to receive the mode.

[0038] In Figure 7 the embodiment of, where parts that are the same as the parts already illustrated are denoted by the same reference numerals, the microelectromechanical membrane transducer 100 includes a discontinuous damper piezoelectric actuator 110 that is delimited by a plurality of different piezoelectric material regions, each piezoelectric material region extending along a corresponding part of the inner periphery of the cantilever damper 107 in the form of an annular sector. The parts of the damper piezoelectric actuator 110 are concentric and have the same radius, and in addition, are individually connected to the drive device 12. In one embodiment, the parts of the damper piezoelectric actuator 110 can be independently controlled by the drive device 12.

[0039] Referring Figure 8 , in a microelectromechanical membrane transducer 200 according to an embodiment of the present disclosure, the cantilever damper 207 includes a plurality of brackets 220 that extend from corresponding anchoring regions 221 towards the membrane 5 and are shaped like annular sectors along corresponding parts of the perimeter of the membrane 5. The brackets 220 are separated from each other by gaps 221. Each bracket 220 is provided with a corresponding damper piezoelectric actuator 210 that includes a piezoelectric material region extending along the corresponding annular sector. The damper piezoelectric actuators 210 can be separately controlled by the drive device 12.

[0040] Figure 9 A microelectromechanical membrane transducer 300 according to an embodiment of the present disclosure is shown. The microelectromechanical membrane transducer 300 includes a perforated membrane 305 and a membrane piezoelectric transducer 308 having a star shape with radial arms. In additional embodiments (not illustrated), the damper piezoelectric actuator can include concentric regions of piezoelectric material having a circular shape or the shape of an annular sector.

[0041] Figures 10 - 14 A process for manufacturing the membrane piezoelectric transducer 1 is schematically shown.

[0042] The first semiconductor wafer 500 ( Figure 10 ) includes a substrate 501 of single-crystalline silicon, on which a structure of a protective layer 13 and a film 5 is continuously formed (for example, via the growth of a pseudo-epitaxial layer of single-crystalline silicon, and the film 5 will be released later), and a protective layer 14. Next, a stack formed of a platinum layer, a piezoelectric material (such as PZT) layer, and a titanium-tungsten alloy (TiW) layer is deposited on the protective layer 14 and defined to form a first film electrode 16, a film piezoelectric actuator 8, and a second film electrode 17. Then, a passivation layer is provided by depositing a USG layer 18 and a silicon nitride layer 19.

[0043] The second semiconductor wafer 510 ( Figure 11 ) includes a substrate 511 of single-crystalline silicon. A silicon oxide layer is formed on the substrate 511 and defined to leave an anchoring region 21a and a stop region 25a, where the anchoring region 21 and the stop element 25 will be formed later. Then an epitaxial layer 513 is grown, and a silicon oxide layer is formed on the epitaxial layer 513 and then defined to provide a bracket 20 having a central opening 515 corresponding to the film 5.

[0044] Next, a stack formed of a platinum layer, a piezoelectric material (such as, PZT) layer, and a titanium-tungsten alloy (TiW) layer is deposited on the protective layer 14 and defined to form a first damper electrode 26, a damper piezoelectric actuator 10, and a second damper electrode 27.

[0045] Then, a passivation layer is obtained by depositing a USG layer 28 and a silicon nitride layer 29 to coat the damper piezoelectric actuator 10, the damper electrodes 26, 27, and the remaining part of the bracket 20. Inside the bracket 20, the passivation layer is selectively removed.

[0046] Then the second semiconductor wafer 510 is bonded to an auxiliary support wafer 515 through an adhesive layer 516, and the substrate 511 is thinned to a controlled thickness.

[0047] Next, the substrate 511 and the epitaxial layer 513 are etched using anisotropic dry etching. In this step, the substrate 511 is completely removed, while the epitaxial layer 513 is partially protected by the anchoring region 21a and the stop region 25a. The anchoring region 21 and the stop element 25 are thus formed.

[0048] The first semiconductor wafer 500 and the second semiconductor wafer 510 are bonded together through an adhesive layer 23, flipped, and the substrate 501 of the first semiconductor wafer 500 is anisotropically etched using dry etching until one side of the film 5 is released.

[0049] Finally, by removing the adhesive layer 516, the second semiconductor wafer 510 is separated from the auxiliary support wafer 515. Figure 2 The structure of the film piezoelectric transducer 1 illustrated in Figure 2 is thus obtained.

[0050] Finally, it is apparent that modifications and variations can be made to the microelectromechanical film transducer, control method, and manufacturing process described herein without departing from the scope of the present disclosure.

[0051] The microelectromechanical film transducer can be generally summarized as including: a support structure (2); a cavity (3) formed in the support structure (2); a membrane (5; 305) coupled to the support structure (3) to cover the cavity (3) on one side; a cantilever damper (7) fixed to the support structure (2) around the perimeter of the membrane (5; 305) and extending toward the interior of the membrane (5; 305) at a distance from the membrane (5; 305); and a damper piezoelectric actuator (10; 110; 210) disposed on the cantilever damper (7) and configured to bend the cantilever damper (7) toward the membrane (5; 305) in response to an electroactuation signal (SD).

[0052] The damper piezoelectric actuator (10; 110; 210) can extend along the inner peripheral edge of the cantilever damper (7).

[0053] The damper piezoelectric actuator (10) can be continuous along the entire inner peripheral edge of the cantilever damper (7).

[0054] The damper piezoelectric actuators (110; 210) can include a plurality of different piezoelectric material regions, each piezoelectric material region being disposed along a corresponding portion of the perimeter of the inner peripheral edge of the cantilever damper (7).

[0055] The cantilever damper (7) can include a bracket (5; 305) that is fixed to the support structure (2) along the perimeter of the membrane (5; 305), and wherein the damper piezoelectric actuator (110; 210) is disposed on the face of the bracket (5; 305).

[0056] The cantilever damper (7) can include a stop element (25) that extends from the inner edge of the bracket (20) toward the membrane (5), and wherein the damper piezoelectric actuator (110) is disposed on the face of the bracket (5; 305) opposite the membrane (5).

[0057] The cantilever damper (7) can include an anchoring region (21) that is joined to the support structure (2) around the membrane (5) by an adhesive layer (23), and wherein the bracket (20) projects from the anchoring region (21).

[0058] The cantilever damper (207) may include a plurality of brackets (220) that extend from respective anchoring regions (221) towards the membrane (5) along respective portions of the perimeter of the membrane (5), and wherein each bracket (220) is provided with a respective damper piezoelectric actuator (210).

[0059] The transducer may include a drive device (12) configured to apply an electro - actuation signal (SD) to the damper piezoelectric actuator (10; 110; 210).

[0060] Each portion of the damper piezoelectric actuator (110) may be independently controlled by the drive device (12).

[0061] Each damper piezoelectric actuator (210) may be independently controlled by the drive device (12).

[0062] The transducer may include a membrane piezoelectric actuator (8; 308) on a face of the membrane (5; 30), wherein the drive device (12) is configured to alternately apply a membrane actuation signal (SM) to the membrane piezoelectric actuator (8; 308) in a transmission mode and receive a received signal (SR) from the membrane piezoelectric actuator (8; 308) in a reception mode.

[0063] The drive device (12) may be configured to cause the membrane actuation signal (SM) to oscillate between a first membrane value (VMINM) and a second membrane value (VMAXM) for a programmed number of cycles, and modify the damper actuation signal (SD) between a first damper value (VMIND) and a second damper value (VMAXD) according to a ramp, so as to gradually bring the cantilever damper (7) into contact with the membrane (5; 305) after the programmed number of cycles of the membrane actuation signal (SM) have been completed.

[0064] A method for controlling a micro - electromechanical membrane transducer may be generally summarized as including: forcing the membrane (5; 305) to oscillate for a programmed number of cycles; and bringing the cantilever damper (7) into contact with the membrane (5; 305) after the programmed number of cycles of oscillation of the membrane (5; 305) have been completed and before the damping transient of the oscillation of the membrane (5; 305) ends.

[0065] The process for manufacturing a microelectromechanical membrane transducer can be generally summarized as including: forming a structure of a membrane (5) on a first substrate (501) of a first semiconductor wafer (500); forming a cantilever damper (7) on a second substrate (511) of a second semiconductor wafer (510), having a central opening (515) at a position corresponding to the structure of the membrane (5); bonding the first semiconductor wafer (500) and the second semiconductor wafer (510), wherein the structure of the membrane (5) faces the cantilever damper structure (7); and releasing the membrane (5; 305), wherein forming the cantilever damper (7) includes forming a damper piezoelectric actuator (10; 110; 210), which is configured to bend the cantilever damper (7) towards the membrane (5; 305) in response to an electrical drive signal (SD).

[0066] The various embodiments described above can be combined to provide further embodiments. Aspects of the embodiments can be modified to provide still further embodiments.

[0067] Based on the above detailed description, these and other changes can be made to the embodiments. In general, in the following claims, the terms used should not be construed as limiting the claims to the specific embodiments disclosed in the specification and claims, but should be construed to include all possible embodiments together with the full scope of equivalents to which the claim is entitled. Thus, the claims are not limited by the present disclosure.

Claims

1. A microelectromechanical membrane transducer, comprising: A support structure; A cavity within the support structure; A membrane coupled to the support structure and covering the cavity on one side; A cantilever damper fixed to the support structure around the periphery of the membrane and extending in a first direction towards the center of the membrane at a distance from the membrane in a second direction; And A damper piezoelectric actuator disposed on the cantilever damper and configured to bend the cantilever damper towards the membrane in response to an electroactuation signal.

2. The transducer according to claim 1, wherein the damper piezoelectric actuator extends along the inner periphery of the cantilever damper.

3. The transducer according to claim 2, wherein the damper piezoelectric actuator is continuous along the entire periphery of the inner periphery of the cantilever damper.

4. The transducer according to claim 2, wherein the damper piezoelectric actuator comprises a plurality of different piezoelectric material regions, each piezoelectric material region being disposed along a corresponding portion of the periphery of the inner periphery of the cantilever damper.

5. The transducer according to claim 1, wherein the cantilever damper comprises a bracket fixed to the support structure along the periphery of the membrane, and wherein the damper piezoelectric actuator is provided on a face of the bracket.

6. The transducer according to claim 5, wherein the cantilever damper comprises a stop element extending from an inner edge of the bracket towards the membrane, and wherein the damper piezoelectric actuator is provided on a face of the bracket opposite to the membrane.

7. The transducer according to claim 5, wherein the cantilever damper comprises an anchoring region joined to the support structure around the membrane by an adhesive layer, and wherein the bracket projects from the anchoring region.

8. The transducer according to claim 5, wherein the cantilever damper comprises a plurality of brackets extending from corresponding anchoring regions towards the membrane along corresponding portions of the periphery of the membrane, and wherein each bracket is provided with a corresponding damper piezoelectric actuator.

9. The transducer according to claim 1, comprising a driving device configured to apply the electroactuation signal to the damper piezoelectric actuator.

10. The transducer according to claim 4, comprising a driving device configured to apply the electroactuation signal to the damper piezoelectric actuator, wherein each part of the damper piezoelectric actuator is independently controlled by the driving device.

11. The transducer according to claim 8, comprising a driving device configured to independently apply the electroactuation signal to each damper piezoelectric actuator.

12. The transducer according to claim 9, comprising a membrane piezoelectric actuator on a face of the membrane, wherein the driving device is configured to: alternately apply a membrane actuation signal to the membrane piezoelectric actuator in a transmission mode and receive a received signal from the membrane piezoelectric actuator in a reception mode.

13. The transducer according to claim 12, wherein the drive device is configured to cause the membrane actuation signal to oscillate a programmed number of cycles between a first membrane value and a second membrane value, and to modify the damper actuation signal between a first damper value and a second damper value according to a ramp, so that after the programmed number of cycles of the membrane actuation signal have been completed, the cantilever damper gradually contacts the membrane.

14. A microelectromechanical membrane transducer, comprising: a cavity in a substrate; a membrane above the cavity; a cantilever damper above a periphery of the membrane, the cantilever damper including a first end and a second end, the first end being coupled to the substrate, and the second end overlapping the cavity and being spaced apart from the membrane by a distance; and a damper piezoelectric actuator disposed on the cantilever damper, and the damper piezoelectric actuator being configured to bend the cantilever damper toward the membrane in response to an electroactuation signal.

15. The transducer according to claim 14, comprising a membrane piezoelectric actuator on the membrane.

16. The transducer according to claim 15, wherein the membrane piezoelectric actuator comprises: a first membrane electrode, a second membrane electrode, and a piezoelectric material plate between the first membrane electrode and the second membrane electrode.

17. The transducer according to claim 15, further comprising a passivation layer above the membrane, the membrane piezoelectric actuator being located between the passivation layer and the membrane.

18. The transducer according to claim 17, wherein the passivation layer comprises an undoped silicate glass layer and a silicon nitride layer.

19. A method for manufacturing a microelectromechanical membrane transducer, comprising: forming a structure of a membrane on a first substrate of a first semiconductor wafer; forming a cantilever damper on a second substrate of a second semiconductor wafer; bonding the first semiconductor wafer and the second semiconductor wafer, wherein the structure of the membrane faces the cantilever damper structure, and a central opening of the cantilever damper structure is located at a position corresponding to the structure of the membrane; and releasing the membrane by forming a cavity in the first substrate below the structure of the membrane; wherein forming the cantilever damper includes: forming a damper piezoelectric actuator configured to bend the cantilever damper toward the membrane in response to an electroactuation signal.

20. The method according to claim 19, comprising: forming a stack of a platinum layer, a piezoelectric material layer, and a titanium tungsten alloy layer on the structure of the membrane.

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