Piezoelectric actuator with deformable structure for improving mechanical properties and method of manufacturing thereof

Abstract

Embodiments of this disclosure relate to a piezoelectric actuator with a deformable structure having improved mechanical properties and a method of manufacturing the same. The MEMS actuator is formed by a body surrounding a cavity and a deformable structure suspended on the cavity and consisting of a movable portion and a plurality of deformable elements. The deformable elements are arranged sequentially to each other, connecting the movable portion to the body, and each deformable element undergoes deformation. The MEMS actuator also includes at least one set of a plurality of actuation structures supported by the deformable elements and configured such that the translation of the movable portion is greater than the deformation of each deformable element. Each actuation structure has a corresponding first piezoelectric region.

Description

Technical Field

[0001] This disclosure relates to a piezoelectric actuator with a deformable structure having improved mechanical properties and a method for manufacturing the same. In particular, reference is made to piezoelectric actuators manufactured using MEMS (Micro-Electro-Mechanical Systems) technology, such as liquid flow control valves, microsprings for loudspeakers, micromirrors, and microtools such as microtweezers or microscissors. Background Technology

[0002] As is known, MEMS actuators are electronic devices typically made of wafers of semiconductor materials (such as silicon) that are capable of causing deformation of movable elements such as diaphragms or cantilever arms.

[0003] MEMS actuators can operate according to different actuation principles, including electrostatic, electromagnetic, and piezoelectric actuation. Specifically, MEMS actuators operating on the piezoelectric actuation principle differ in their high energy efficiency and high deformation accuracy of the movable element; therefore, piezoelectric MEMS actuators are becoming increasingly popular.

[0004] In addition, actuators with piezoelectric actuation systems are known for use in the manufacture of devices such as microfluidic valves used in flow control devices, micromirrors, and precision surgical instruments.

[0005] In the following text, a flow regulator will be referenced by way of example. A flow regulator is a device that allows control of the amount of fluid flowing within a fluid channel, and flow regulators can be used, for example, at an industrial level, to control process parameters of machines used to manufacture semiconductor devices.

[0006] Typically, a flow regulator includes a fluid passage with an inlet and an outlet, a valve that regulates the amount of fluid flowing in the fluid passage, a flow meter that measures the flow rate of the fluid in the fluid passage, and a control unit. Summary of the Invention

[0007] This disclosure discloses a piezoelectric actuator that overcomes the limitations of known solutions, and in particular, allows for a reduced size and lower bias voltage compared to known solutions.

[0008] According to this disclosure, a piezoelectric actuator and a method for manufacturing the same are provided.

[0009] At least one embodiment of the MEMS actuator disclosed herein relates to a MEMS actuator comprising a body surrounding a cavity. A deformable structure on the cavity includes a movable portion and a plurality of deformable elements arranged sequentially. The plurality of deformable elements connect the movable portion to the body. The deformable structure also includes a plurality of arms coupling the movable portion, the plurality of deformable elements, and the body together. The deformable structure further includes a plurality of reinforcing structures, a respective reinforcing structure being integrated with a respective arm of the plurality of arms. The MEMS actuator also includes at least one set of a plurality of actuation structures on the deformable elements.

[0010] At least one embodiment of the flow regulator disclosed herein relates to a flow regulator including a channel body, a fluid channel within the channel body and having an end portion, and a passage cross-section adjacent to the end portion. The flow regulator also includes a microelectromechanical system (MEMS) actuator having a cavity, a body surrounding the cavity, and a deformable structure aligned with the cavity. The deformable structure includes a movable portion having a surface facing the end portion and configured to change the passage cross-section disposed between the end portion and the movable portion. The deformable structure also includes a plurality of deformable elements surrounding the movable portion, at least one set of a plurality of actuation structures on the plurality of deformable elements, and at least one detection structure on the plurality of deformable elements. The flow regulator also includes a control unit coupled to the MEMS actuator, the control unit being configured to provide a bias voltage to the at least one set of actuation structures and receive a detection voltage from the at least one detection structure.

[0011] At least one embodiment of the loudspeaker disclosed herein relates to a loudspeaker including a housing defining a first cavity, a diaphragm attached to the housing and on the cavity, and a MEMS actuator. The MEMS actuator includes a second cavity, a body surrounding the second cavity, and a deformable structure coupled to the diaphragm and configured to cause deformation of the diaphragm. The deformable structure includes a movable portion coupled to the diaphragm, a plurality of deformable elements surrounding the movable portion, at least one set of a plurality of actuation structures on the plurality of deformable elements, and at least one detection structure on the plurality of deformable elements. The loudspeaker also includes a control unit coupled to the MEMS actuator and configured to: provide a bias voltage to the at least one set of actuation structures and receive a detection voltage from the at least one detection structure.

[0012] At least one embodiment of the method disclosed herein relates to fabricating a MEMS actuator, comprising forming at least one set of a plurality of actuation structures on a first surface of a substrate opposite a second surface of the substrate. Forming the deformable structure includes forming a movable portion, forming a plurality of deformable elements arranged sequentially relative to each other and connecting one of the plurality of deformable elements to the movable portion, and forming a frame and connecting the frame to one of the plurality of deformable elements by forming a cavity extending into the second surface of the substrate. Attached Figure Description

[0013] To better understand this disclosure, embodiments of the disclosure will now be described by way of non-limiting example only, with reference to the accompanying drawings, in which:

[0014] Figure 1 The cross-section of the flow regulator is known.

[0015] Figure 2A This is a perspective view taken from above of an embodiment of the piezoelectric actuator of the present invention;

[0016] Figure 2B yes Figure 2A The deformation sensor of the piezoelectric actuator moves along when stationary Figure 4A The cross section intercepted by the cross section line IIA-IIA;

[0017] Figure 3 From Figure 2A A perspective view of the piezoelectric actuator from below;

[0018] Figure 4A yes Figure 2A A top view of the piezoelectric actuator;

[0019] Figure 4B yes Figure 2A The actuating element of the piezoelectric actuator moves along when stationary. Figure 4A The cross section intercepted by the cross-section line IVA-IVA;

[0020] Figure 4C yes Figure 4B The actuating element moves along the deformation condition Figure 4A The cross section intercepted by the cross-section line IVA-IVA;

[0021] Figure 5 yes Figure 2A A perspective view of the piezoelectric actuator in use according to the first operating mode;

[0022] Figure 6 yes Figure 2A A perspective view of the piezoelectric actuator in use according to the second operating mode;

[0023] Figure 7 It is a combination Figure 2A A schematic cross-section of the flow regulator of a piezoelectric actuator when at rest;

[0024] Figure 8 Showing under different operating conditions Figure 7 Flow regulator;

[0025] Figure 9 It is a combination Figure 2A Schematic cross-section of different flow regulators of a piezoelectric actuator at rest;

[0026] Figure 10 Showing under different operating conditions Figure 9 Flow regulator;

[0027] Figure 11 This is a schematic cross-section of a flow regulator in rest, incorporating another embodiment of the piezoelectric actuator of the present invention.

[0028] Figure 12 This is a simplified perspective view of a loudspeaker incorporating the piezoelectric actuator of the present invention; and

[0029] Figure 13A-21A And 13B-21B respectively show Figure 2A The piezoelectric actuator is manufactured in a continuous process along... Figure 4A The cross sections taken by the cross-section lines XIIIA-XIIIA and XIIIB-XIIIB. Detailed Implementation

[0030] This disclosure relates to at least one embodiment of a piezoelectric actuator and at least one embodiment of a method for manufacturing the same. Details will be discussed further herein.

[0031] Figure 1 The structure of a known flow regulator 10, for example using piezoelectric actuation, is shown. The flow regulator 10 includes a body 11; a fluid passage 12 extending into the body 11 and having an inlet 13 and an outlet 14; a valve 15; a flow meter 16; and a control unit 20.

[0032] The fluid channel 12 here includes first and second horizontal portions 21A and 21B, which are continuously coupled to inlet 13 and outlet 14 via first vertical portion 22, passage 23 and second vertical portion 24, respectively. Based on Figure 1 The orientation of the flow regulator 10 in the fluid channel 12 is such that portions 21A and 21B are described as horizontal, and portions 22 and 24 are described as vertical.

[0033] The first vertical portion 22 extends in the region of the valve 15 between the first horizontal portion 21A and the surface 11A of the body 11, as explained below; the second vertical portion 24 extends in the region of the valve 15 between the surface 11A of the body 11 and the second horizontal portion 21B, and is separated from the first vertical portion 22 by the wall 25 of the body 11.

[0034] Flow meter 16 is coupled to a first horizontal portion 21A of fluid passage 12 and control unit 20. Flow meter 16 is configured to measure a quantity associated with the amount of fluid flowing in fluid passage 12. For example, flow meter 16 may include a resistor ( Figure 1 (Not shown in the image), the resistor is arranged along the fluid channel 12 in a known manner and has resistance associated with the existing flow.

[0035] The valve 15 includes a support 27 engaged with the body 11, a diaphragm 26 engaged with the support 27, and a piezoelectric actuation system 28 carried by the diaphragm 26.

[0036] In detail, the diaphragm 26 is formed of, for example, a metallic material, is constrained to the body 11 by a support 27, and is suspended on the first vertical portion 22 and the second vertical portion 24 and the wall 25 and faces the first vertical portion, the second vertical portion and the wall, thereby forming a passage 23 of the fluid channel 12 together with the wall.

[0037] The piezoelectric actuation system 28 is coupled to the control unit 20 and changes the distance between the diaphragm 26 and the wall 25 to change the flow.

[0038] In use, a certain amount of fluid flows through the fluid channel 12; this certain amount can be a selected quantity. In this regard, the control unit 20 applies a bias voltage to the piezoelectric actuation system 28, thereby causing deformation of the diaphragm 26. Consequently, the cross-section of the passage 23 changes, thus altering the amount of fluid flowing in the fluid channel 12.

[0039] In particular, the distance between the diaphragm 26 and the wall 25 can be continuously adjusted by modulating the bias voltage applied to the piezoelectric actuation system 28; therefore, the valve 15 can take multiple operating states ranging from a fully closed state to a fully open state, corresponding to zero and maximum fluid volumes proportional to the value of the bias voltage, respectively.

[0040] Meanwhile, the control unit 20 measures the fluid flow rate in the fluid channel 12 and can control the opening degree of the valve 15 based on the measured flow rate.

[0041] However, as Figure 1 The flow regulator 10 shown has disadvantages.

[0042] For example, the flow regulator 10 has a larger size than the embodiments of the flow regulators disclosed herein. In fact, the flow meter 16 is placed at a certain distance from the valve 15.

[0043] Furthermore, the piezoelectric actuation system 28 has a large size. For example, a piezoelectric mass block manufactured using bulk technology can have a thickness of even several millimeters. Therefore, the actuation system 28 is not suitable for applications where high miniaturization is beneficial.

[0044] Furthermore, the piezoelectric actuation system 28 includes high bias voltages, even hundreds of volts, to achieve deformations of tens of micrometers. Such high bias voltages may require complex and expensive integration processes in the aforementioned devices and could pose a danger to the user of the flow regulator 10.

[0045] Furthermore, the flow regulator 10 has low energy efficiency because the flow meter 16 performs active detection of fluid flow, i.e., through an electrical path. Therefore, the flow regulator consumes a significant amount of energy.

[0046] This disclosure relates to embodiments of piezoelectric actuators fabricated using the piezoelectric film MEMS (microelectromechanical systems) technology described herein. For example, piezoelectric actuator 50 is fabricated using the piezoelectric film MEMS technology as described herein.

[0047] like Figure 2A , Figure 3 and Figure 4A As shown, the piezoelectric actuator 50 is formed in a body 51 having a first surface 51A and a second surface 51B, and includes a substrate 57 of a semiconductor material (e.g., silicon), a surface layer 58 covering the substrate 57, the surface layer being formed, for example, by a plurality of monolayers, the monolayers being, for example, layers of semiconductor material (e.g., polycrystalline silicon), and at least one layer of insulating material, such as tetraethyl orthosilicate (TEOS).

[0048] For example, a cylindrical cavity 52 extends from the second surface 51B into the interior of the body 51 and passes completely through the body 51. Therefore, the portions of the substrate 57 and the surface layer 58 on the substrate form a frame 53 surrounding the deformable structure 54, which is here formed of the same material as the material that forms the surface layer 58 and is suspended on the cavity 52.

[0049] The surface layer 58 is much thinner than the horizontal extension of the first face 51A of the substrate 57 and the deformable structure 54, which is substantially parallel to the body 51.

[0050] Therefore, the deformable structure 54 is basically planar.

[0051] The deformable structure 54 is symmetrical in the plan view, for example, circularly symmetrical with a center O or a polygon with a large number of symmetrical sides, and includes a plurality of deformable rings 55 concentric with each other, and a movable central portion 56 surrounded by the deformable rings 55 and having a circular cross section in the plan view.

[0052] In particular, in this embodiment, the deformable structure 54 is composed of three deformable rings, including first, second and third deformable rings 55A-55C.

[0053] The first ring 55A is coupled to the frame 53 via a plurality of first connecting portions 60. Each first connecting portion 60 is suspended on and overlaps with the cavity 52, and each first connecting portion 60 extends between the frame 53 and the first deformable ring 55A, forming a single piece (or integral) therewith.

[0054] In detail, there are three first connecting parts 60, spaced 120° apart from each other along the circumference of the first deformable ring 55A.

[0055] The second deformable ring 55B is arranged internally relative to the first deformable ring 55A, such that the first deformable ring 55A surrounds the second deformable ring 55B. The second deformable ring 55B is coupled to the first deformable ring 55A via a plurality of second connecting portions 65. Each second connecting portion 65 is suspended on and overlaps with the cavity 52, and each second connecting portion 65 extends between the first and second deformable rings 55A and 55B, forming a single piece therewith.

[0056] In detail, there are three second connecting portions 65, which are spaced 120° apart from each other along the circumference of the second deformable ring 55B, and in this embodiment have an offset of 60° relative to the first connecting portion 60.

[0057] The third deformable ring 55C is arranged internally relative to the second deformable ring 55B and coupled to the second deformable ring 55B via a plurality of third connecting portions 70. Each third connecting portion 70 is suspended on and overlaps with the cavity 52 and extends between the second and third deformable rings 55B and 55C, forming a single piece therewith.

[0058] Specifically, there are three third connecting portions 70, which are spaced 120° apart from each other along the circumference of the third deformable ring 55C, and in this embodiment have an offset of 60° relative to the second connecting portion 65. In other words, the third connecting portions 70 have zero offset relative to a corresponding first connecting portion of the first connecting portions 60, and are radially aligned with a corresponding first connecting portion of the first connecting portions 60.

[0059] The third deformable ring 55C is also coupled to the movable central portion 56 via multiple fourth connecting portions 75. Each fourth connecting portion 75 is suspended on the cavity 52 and extends between the third deformable ring 55C and the movable central portion 56, forming a single piece therewith.

[0060] Specifically, there are three fourth connecting portions 75, which are spaced 120° apart from each other along the circumference of the third ring 55C, and in this embodiment have an offset of 60° relative to the third connecting portion 70. In other words, the fourth connecting portions 75 have zero offset relative to a corresponding second connecting portion of the second connecting portions 65, and are radially aligned with the corresponding first connecting portion of the second connecting portions 65.

[0061] The first, second and third deformable rings 55A-55C carry a plurality of corresponding actuating structures 80, which are equal in number to each other, have the shape of curved bands, and are operably divided into a first group and a second group of actuating structures 80A, 80B and placed at a certain distance from each other.

[0062] Each actuation structure 80 (see section 80A for the first group of actuation structures) Figure 4B The capacitor is formed by a stack including a lower actuating electrode 81 made of a conductive material, such as platinum; a piezoelectric actuating region 82 made of a single-crystal ceramic material having a high relative permittivity (e.g., greater than 100), such as lead zirconate titanate (PZT), BaTiO3, KNN (potassium sodium niobate), PbTiO2, or PbNb2O6; and an upper actuating electrode 83 made of a conductive material, such as platinum, iridium oxide, yttrium, or a titanium-tungsten alloy. The piezoelectric actuating region 82 is arranged between the upper actuating electrode 83 and the lower actuating electrode 81 to form a capacitor structure.

[0063] In detail, here, the lower actuation electrode 81 of all actuation structures 80 consists of a single conductive region ( Figure 2A The conductive region (not visible in the middle) includes a connection portion 87 (only partially visible here) for connecting to the lower electrode pad 88, for electrical connection to an external bias circuit (not shown), such as a connection to a reference potential (ground).

[0064] The upper actuation electrode 83 of the first set of actuation structures 80A is connected to the corresponding first set of upper electrode pads 90A via the first conductive connection rail 89A (only partially visible here) for electrical connection to an external bias circuit.

[0065] The upper actuation electrode 83 of the second set of actuation structures 80B is connected to the corresponding second set of upper electrode pads 90B via the second conductive connection rail 89B (only partially visible here) for electrical connection to an external bias circuit.

[0066] In this embodiment, each of the first, second, and third deformable rings 55A-55C carries six actuation structures 80. The curved bands forming the actuation structures 80 each cover substantially equal circumferential arcs and have a center C located on a centerline, which is based on... Figure 4A The orientation of the piezoelectric actuator 50 is defined by an arc and in Figure 4A The middle is represented by a dashed line, and this dashed line is in Figure 4A The center C passes through the left side of the actuating structure 80. The center C of each actuating structure 80 is equidistant from the center C of the corresponding adjacent actuating structure 80. In other words, the center C of the actuating structures 80 are spaced 60° apart from each other along the circumference of the corresponding deformable ring 55, and the actuating structures 80 of each deformable ring 55A-55C have equal lengths and are radially aligned with the actuating structures 80 of the adjacent deformable rings 55A-55C.

[0067] The first and second sets of actuating structures 80A and 80B are arranged alternately and continuously in each deformable ring 55A-55C; in particular, the center C of the second set of actuating structures 80B is spaced 120° apart from each other along the circumference of the corresponding deformable ring 55, and has an offset of 60° relative to the center C of the corresponding adjacent first set of actuating structures 80A in the same deformable ring 55.

[0068] Furthermore, the center C of the first set of actuation structures 80A of the first deformable ring 55A is offset by 60° relative to the center C of the first set of actuation structures 80A of the second deformable ring 55B and has zero offset relative to the center C of the first set of actuation structures 80A of the third deformable ring 55C (in other words, they are radially aligned with that center).

[0069] In addition, deformable rings 55A-55C support multiple reinforcing structures 85 ( Figure 3 and Figure 4A The reinforcing structure extends from the underside of the deformable ring 55 toward the interior of the cavity 52. ​​The reinforcing structure 85 (one reinforcing structure for each of the first set of actuating structures 80A) extends radially, each reinforcing structure aligned with the center C of the corresponding first set of actuating structures 80A and located on the underside of the corresponding connecting portion; therefore, the radial width of each reinforcing structure 85 is substantially equal to the sum of the widths of the corresponding deformable ring 55 and the corresponding connecting portion.

[0070] The reinforcing structure 85 is a single piece (or an integral part) with corresponding connecting parts (as explained below with reference to the manufacturing method) and is therefore integrated with the corresponding connecting parts.

[0071] In fact, the reinforcing structure 85 and the corresponding connecting parts function as a pivoting structure in use, as explained in detail below.

[0072] In this embodiment, each of the deformable rings 55A-55C carries three reinforcing structures 85, which are spaced 120° apart from each other along the circumference of the respective deformable ring 55. Specifically, with respect to the first deformable ring 55A, each reinforcing structure 85 is integrated with a corresponding first connecting portion 60; with respect to the second deformable ring 55B, each reinforcing structure 85 is integrated with a corresponding second connecting portion 65; and with respect to the third deformable ring 55C, each reinforcing structure 85 is integrated with a corresponding third connecting portion 70.

[0073] In addition, the movable central part 56 carries the shutter structure 86. Figure 3 and Figure 4A The opening / closing structure is formed in the same layer as the reinforcing structure 85, extending towards the interior of the cavity 52 below the movable central portion 56. Here, the opening / closing structure 86 has a circular cross-section in plan view, the diameter of which is less than or substantially equal to the cross-section of the movable central portion 56. The opening / closing structure 86 has a region that protrudes from the movable central portion 56 toward the cavity 52 and enters the cavity. The movable central portion 56 may be a platform suspended on and overlapping the cavity 52.

[0074] The deformable structure 54 also houses multiple deformation sensors, three of which are 91. Figure 2A As shown in the diagram. The deformation sensor 91 can be a detection structure or some other similar or analogous sensor.

[0075] The deformation sensors 91 are each carried by a corresponding deformable ring 55 and are arranged between two adjacent actuation structures 80. In particular, in this embodiment, each of the deformable rings 55A-55C carries one deformation sensor 91.

[0076] The deformation sensors 91 are formed by respective stacks, each stack including a lower detection electrode 92 made of a conductive material such as platinum, a piezoelectric detection region 93, and an upper detection electrode 94 made of a conductive material such as molybdenum, platinum, iridium oxide, or yttrium. The piezoelectric detection region is made of materials having, for example, a low relative permittivity of about 10 or substantially equal to 10, and a loss tangent of, for example, less than 0.05, particularly substantially equal to 0.002, such as aluminum nitride, zinc oxide, or polyvinylidene fluoride (PVDF) (here, aluminum nitride). The piezoelectric detection region 93 is arranged between the upper detection electrode 94 and the lower detection electrode 92 to form a capacitor structure, such as... Figure 2B As shown.

[0077] In this embodiment, the lower detection electrode 92 of each deformation sensor 91 is formed by the same single conductive region forming the lower actuation electrodes 81 of all actuation structures 80. Furthermore, the third conductive connection track 95, shown only partially here, connects the upper detection electrode 94 to the detection pad 96 (see [link to documentation]). Figure 2A ), for use in electrical connection to an external measurement circuit (not shown).

[0078] The deformable structure 54 can form, for example, a normally closed or normally open valve structure, which is controlled to be fully open or fully closed or to be in flow modulation, as explained in detail below.

[0079] Specifically, in use, without bias voltage, the piezoelectric actuator 50 is in... Figure 2A , Figure 3 and Figure 4A The position shown indicates that the upper surface of the movable central portion 56 is flush with the first surface 51A of the body 51. In other words, when the piezoelectric actuator 50 is stationary, the movable central portion 56, the deformable elements 55A, 55B, 55C of the deformable structure 55, and the upper surface of the body 51 are substantially coplanar with each other in a plane, such that the upper surfaces are aligned with each other.

[0080] To move the movable central portion 56 away from or toward the cavity 52, a bias voltage is selectively applied between the upper electrode 83 and the lower electrode 81 of the actuation structure 80, as explained below. In particular, the bias voltage causes deformation of the piezoelectric actuation region 82, for example... Figure 4C The first set of actuation structures 80A is shown in the figure. In fact, regardless of the polarity of the bias voltage, the piezoelectric actuation region 82 undergoes equal warping deformation, wherein the central portion of the actuation structure 80 is lowered relative to the side portion of the same actuation structure 80.

[0081] However, the different positions of the first set of actuation structures 80A (the central part of the first set of actuation structures is constrained by the first, second and third connecting parts 60, 65 and 70 and by the reinforcing structure 85) relative to the second set of actuation structures 80B determine the different deformations of the deformable ring 55 depending on whether the first set of actuation structures 80A or the second set of actuation structures 80B is biased, as described in detail below.

[0082] exist Figure 5 In this process, a bias voltage V1, especially a positive unipolar bias voltage of, for example, 40V, is applied to the first set of actuation structures 80A, while the second set of actuation structures 80B is not biased (V2 = 0V).

[0083] Under this bias condition, each of the first set of actuation structures 80A approximately behaves as follows: Figure 4C The first deformable ring 55A is deformed as shown.

[0084] As noted, in the first deformable ring 55A, the central portion of the first set of actuating structures 80A is constrained to the frame 53 by the first connecting portion 60 and the corresponding reinforcing structure 85, thus remaining almost undeformed; conversely, the end portions of the first set of actuating structures 80A are lifted upward.

[0085] Lifting the end portion of the first set of actuation structures 80A also causes the adjacent second set of actuation structures 80B of the first deformable ring 55A to be lifted.

[0086] Furthermore, since the central portion of the first set of actuating structures 80A of the second deformable ring 55B is constrained to the central portion of the second set of actuating structures 80B of the first deformable ring 55A (via the second connecting portion 65 and the corresponding reinforcing structure 85), they are lifted, thus lifting the inner deformable rings (the second and third deformable rings 55B and 55C) for this reason. Moreover, the first set of actuating structures 80A of the second deformable ring 55B deforms similarly to that described above, causing a further lift of the second set of actuating structures 80B of the second deformable ring 55B and thus a further lift of the third deformable ring 55C.

[0087] Similarly, the first set of actuating structures 80A of the third deformable ring 55C deforms and causes a further lift of the second set of actuating structures 80B of the third deformable ring 55C, and thus causes a further lift of the movable central portion 56, as in Figure 5 As shown in the figure, the piezoelectric actuator 50 is represented in grayscale, where the darker parts are those that deform more relative to the stationary position.

[0088] exist Figure 6 In this process, a bias voltage, particularly a positive unipolar voltage as described above, is applied to the second set of actuation structures 80B. Here, the piezoelectric actuator 50 is again represented in grayscale, where darker shades correspond to larger deformations relative to the rest position.

[0089] In this case, the second set of actuating structures 80B of the first deformable ring 55A deforms, as... Figure 4C As shown, and causes its central portion to displace downward toward the interior of the cavity 52 relative to its end portion, the end portion being constrained to an adjacent first set of actuating structures 80A, the first set of actuating structures being undeformed due to not being biased and being constrained to the frame 53 by a first connecting portion 60 and a corresponding reinforcing structure 85.

[0090] The first set of actuating structures 80A of the second set of actuating structures 80B (via the second connecting portion 65 and the corresponding reinforcing structure 85), which is not biased and is constrained to the second set of actuating structures 80B of the first deformable ring 55A, also moves downward (towards the interior of the cavity 52). Furthermore, the deformation of the second set of actuating structures 80B of the second deformable ring 55B causes a further downward displacement of the corresponding end portion and thus causes a further downward displacement of the third deformable ring 55C towards the interior of the cavity 52.

[0091] Similarly, the deformation of the second set of actuation structures 80B of the third deformable ring 55C causes the movable central portion 56 to further decrease toward the interior of the cavity 52.

[0092] In practice, the deformable structure 54 allows for a high translation of the movable central portion 56 relative to its rest position. This high translation is greater than the deformation of each deformable ring 55 caused by the corresponding actuation structure 80. Both the high translation and the deformation move towards the interior of the cavity 52 and away from the cavity 52. ​​This high displacement can be achieved by applying a low bias voltage.

[0093] The maximum deformation of the deformable structure 54 depends on several factors, including the number of deformable rings 55, the thickness and diameter of the deformable structure 54 and the movable central portion 56, the thickness of the reinforcing structure 85 and the opening / closing structure 86, and the maximum applicable voltage; these factors are parameters that can be modified during the design phase according to the specific application.

[0094] For example, in the simulations performed by the applicant, it has been verified that the movable center section can be translated up to 80 μm with a bias voltage of 40 V (translation of 40 μm in each of the two directions).

[0095] The deformation of the deformable structure 54 allows for vertical displacement of the movable central portion 56 while maintaining the opening / closing structure 86 substantially parallel to its rest position, a feature that can be used in specific applications.

[0096] In addition, refer to again Figure 2A During use, the deformation of the deformable structure 54 generates mechanical stress in the deformable ring 55. This mechanical stress generates a detection voltage in the piezoelectric detection region 93 between the lower detection electrode 92 and the upper detection electrode 94 of each deformation sensor 91. Figure 2B In a known manner, the detection voltage can be measured and passed through a measuring circuit (e.g., Figure 7 (As shown) is converted into the deformation value of the deformable structure 54, and thus into the displacement value of the movable central portion 56 relative to the rest position.

[0097] Therefore, the measurement of the detection voltage allows for the control of the state of the piezoelectric actuator 50 through a closed-loop control system and in real time.

[0098] In addition, the size of the piezoelectric actuator 50 is significantly reduced because the actuation structure 80 and the deformation sensor 91 are both integrated in the same die.

[0099] Furthermore, since the deformation sensor 91 is piezoelectric, the measurement of the detection voltage is passive, meaning it does not imply the passage of current, thus making the piezoelectric actuator 50 energy efficient.

[0100] like Figure 7 As shown, the piezoelectric actuator 50 can be integrated into the flow regulator 200. In addition to the piezoelectric actuator 50, the flow regulator 200 also includes a body 205 and a fluid passage 210, which has an inlet portion 210A and an outlet portion 210B.

[0101] The body 205 is made of a semiconductor material such as silicon and is formed of: a horizontal portion 206, a tubular protrusion 207 extending laterally from the horizontal portion 206, and a through hole 208 having an opening that forms an inlet portion 210A of a fluid channel 210 and passing through the tubular protrusion 207.

[0102] The horizontal portion 206 of the body 205 is joined to the substrate 57 of the piezoelectric actuator 50 via the engagement region 215, such that the horizontal portion 206 of the body 205 faces the cavity 52, and the tubular protrusion 207 is aligned with the opening / closing structure 86. In particular, in this embodiment, the height of the tubular protrusion 207 is such that, when stationary, the opening / closing structure 86 contacts one end of the tubular protrusion 207.

[0103] In addition, the flow regulator 200 includes a control unit 220, which transmits signals via... Figure 2A Contact pads 88, 90A, 90B and 96 (e.g.) Figure 7 (Schematically shown) Coupled to piezoelectric actuator 50, and in particular to actuation structure 80 and deformation sensor 91, for exchanging signals and electrical quantities for controlling flow regulator 200.

[0104] To this end, the control unit 220 includes input / output ports 221, 222 for receiving control signals and sending detection signals to external sources (e.g., towards a user), a control stage 223 (e.g., a CPU) for processing signals provided for control, and a drive stage 224 for controlling the flow regulator 200. The control stage 223 may, for example, store a conversion table between nominal flow rates and corresponding bias voltage values ​​to be supplied to the piezoelectric actuator 50.

[0105] In use, the user can set the nominal flow rate of the fluid in the fluid channel 210 via input port 221. Based on a stored table, the control unit 220 applies a bias voltage of appropriate value to the first set of actuation structures 80A. As previously described and as... Figure 8 As shown, the deformable structure 54 deforms, and the movable central portion 56 (which thus forms a cap element here) moves the opening / closing structure 86 away from the end of the tubular protrusion 207, thereby creating a passage 230 for the fluid channel 210 and separating the deformable ring 55 and the movable central portion 56 in opposite directions, thus forming an outlet portion 210B of the fluid channel 210. Therefore, in Figure 8 In the deformed position, passage 230 connects inlet portion 210A to outlet portion 210B through through hole 208, and thus allows liquid or gas (e.g. fluid) supplied to inlet portion 210A to flow.

[0106] Meanwhile, as mentioned above, the deformation sensor 91 (not shown here) detects the stress generated by the deformation of the deformable structure 54 and provides a corresponding detection voltage to the control unit 220.

[0107] The control unit 220 can then compare the value of the detected voltage (or a related quantity) with an appropriate calibration parameter corresponding to the flow rate value and verify in real time that the fluid flow rate conforms to the nominal value. If not, the control unit 220 can modify the bias voltage to make the flow rate conform to the nominal value.

[0108] Figure 9 and Figure 10 Another embodiment of a flow regulator similar to flow regulator 200 is shown, which is referred to here as 250, and therefore common elements will be indicated by the same reference numerals.

[0109] In detail, the flow regulator 250 includes a piezoelectric actuator 50, a body 255, and a fluid passage 260 having an inlet portion 260A and an outlet portion 260B. Figure 7 Unlike the flow regulator 200, the height of the tubular protrusion 207 is such that when at rest, the end of the tubular protrusion is a certain distance away from the on / off structure 86, and the fluid passage 260 of the flow regulator 250 forms a passage 265 defined by the on / off structure 86 and the tubular protrusion 207 when at rest.

[0110] In this way, fluid can flow between the inlet portion 260A and the outlet portion 260B of the fluid channel 260 without a bias voltage.

[0111] In use, when the flow through fluid channel 260 is altered or obstructed, a bias voltage is applied to actuation structure 80 to set a nominal flow rate value. In this embodiment, a bias voltage is applied to the second set of actuation structures 80B, causing downward displacement of deformable structure 54 and causing the opener / closer structure 86 to move closer to tubular protrusion 207, such as... Figure 10 As shown. In this way, the cross-section of passage 265 is reduced, and therefore the flow rate is reduced; the flow rate can also be completely interrupted when passage 265 is completely closed.

[0112] Figure 11 A flow regulator 270 incorporating the piezoelectric actuator of the present invention, hereinafter referred to as piezoelectric actuator 280, is shown according to another embodiment. Flow regulator 270 and piezoelectric actuator 280 have similar structures to flow regulator 250 and piezoelectric actuator 50, respectively, and therefore common elements are identified by the same reference numerals.

[0113] Specifically, here, the movable central portion 56 directly faces the tubular protrusion 207 and, when stationary, is a certain distance away from the tubular protrusion 207, forming a passage 285. In use, a bias voltage can cause the movable central portion 56 to move closer to or further away from the tubular protrusion 207, thereby changing the cross-section of the passage 285, as previously explained. In fact, here, the passage 285 is defined by the tubular protrusion 207 and the movable central portion 56, and there is no switch structure 86.

[0114] According to another embodiment, the piezoelectric actuators 50 and 280 can be integrated into the speaker.

[0115] Especially in Figure 12 In this design, the speaker 300 includes a piezoelectric actuator 50. However, it will be apparent to those skilled in the art that a piezoelectric actuator 280 can also be integrated into the speaker 300 in a similar manner.

[0116] The loudspeaker 300 includes a housing 303 defining a cavity 305; a support 307 attached to the housing 303; and a diaphragm 306 supported by the support 307 and suspended on the cavity 305.

[0117] The housing 303 is approximately hemispherical or dome-shaped; the support 307 and the diaphragm 306 enclose the housing at the back.

[0118] The speaker 300 also includes an actuator 50 and a control unit 320 disposed inside the housing 305. Alternatively, the control unit 320 may be made outside the housing 303.

[0119] The control unit 320 is coupled to the piezoelectric actuator 50, and in particular to the actuation structure 80, as already referred to, for example. Figure 7Described.

[0120] The movable central portion 56 and the on / off structure 86 of the piezoelectric actuator 50 are mechanically coupled to the diaphragm 306, for example, the movable central portion and the on / off structure are joined to the diaphragm.

[0121] In use, the control unit 320 applies a bias voltage of appropriate frequency to the first and / or second set of actuation structures 80A, 80B, thereby causing displacement of the movable central portion 56 (as previously described) and thus deformation of the diaphragm 306, which oscillates back and forth relative to a plane perpendicular to the plane of the accompanying drawings (i.e., towards the inside and outside of the cavity 305). Therefore, the deformation of the diaphragm 306 generates sound waves that can propagate outside the speaker 300.

[0122] Therefore, due to the characteristics of the piezoelectric actuator 50 described above, the speaker 300 can have a reduced size and high energy efficiency.

[0123] The following will describe the causes of manufacturing Figure 2A The manufacturing steps of the piezoelectric MEMS actuator 50 shown are illustrated.

[0124] especially, Figures 13A-21A The fabrication method of the piezoelectric MEMS actuator 50 at the actuation structure 80, the deformation sensor 91, and part of the deformable structure 54 is shown in a circumferential cross-section taken along the deformable ring 55. Figures 13B-21B The fabrication method of the piezoelectric MEMS actuator 50 at the actuation structure 80 and parts of the deformable structure 54 and frame 53 is shown by radial cross-sections taken through different adjacent deformable rings 55.

[0125] Figure 13A and Figure 13B The image shows a wafer 400 that has undergone the first processing step. Specifically, the wafer 400 includes a working substrate 405 made of a semiconductor material such as silicon, having first and second surfaces 405A and 405B respectively disposed on the front and back sides of the wafer 400. A first forming layer 406, for example made of deposited tetraethyl orthosilicate (TEOS) and having a thickness of at least 1 μm (here, 1 μm), extends on the first surface 405A of the working substrate 405.

[0126] Subsequently, as Figure 14A and Figure 14B As shown, the first forming layer 406 is patterned by selective etching to form a plurality of first lower forming regions 407 and second lower forming regions 408, wherein it is desirable to subsequently form a plurality of reinforcing structures 85 and opening / closing structures 86, as described in detail below.

[0127] Furthermore, a reinforcing layer 409, made of a semiconductor material, such as polysilicon, is formed, for example, epitaxially grown, on the first surface 405A of the working substrate 405, on a plurality of first lower forming regions 407, and on a second lower forming region 408; then, the reinforcing layer 409 is subjected to chemical mechanical polishing (CMP) to form a flat upper surface. The thickness of the reinforcing layer 409 is greater than that of the first forming layer 406, and in this embodiment, for example, is 25 μm.

[0128] Subsequently, a first insulating layer 410, made of, for example, tetraethyl orthosilicate (TEOS) and having a thickness equivalent to that of the first shaped layer 406, such as 1 μm, is deposited on the reinforcing layer 409.

[0129] exist Figure 15A and Figure 15B In this structure, a structural layer 411 made of a semiconductor material such as polycrystalline silicon is deposited on the first insulating layer 410. The structural layer 411 has a thickness selected based on desired mechanical properties; for example, in this embodiment, the structural layer has a thickness of 10 μm.

[0130] For example, a second insulating layer 412 made of tetraethyl orthosilicate (TEOS) and having a thickness of, for example, 0.5 μm is deposited on the structural layer 411.

[0131] Subsequently, Figure 16A and Figure 16B In this process, for example, a first conductive layer 420 made of platinum is deposited on a second insulating layer 412; an actuation layer 421 made of a single-crystal piezoelectric material with a high relative permittivity (e.g., greater than 100) is deposited on the first conductive layer 420, the thickness of the actuation layer being in the range of 1 μm-3 μm, particularly for example, 2 μm, the single-crystal piezoelectric material being such as lead zirconate titanate (PZT), BaTiO3, KNN (potassium sodium niobate), PbTiO2 or PbNb2O6; a second conductive layer 422 made of, for example, tungsten titanium alloy, platinum, yttrium or iridium oxide is deposited on the actuation layer 421, forming a stack of layers.

[0132] The resulting stack of layers is patterned using photolithography and selective etching steps known to those skilled in the art, such that a first conductive layer 420 forms a lower electrode region 415, an actuation layer 421 forms a plurality of first piezoelectric regions 416, and a second conductive layer 422 forms a plurality of upper electrode regions 417.

[0133] In particular, multiple upper electrode regions 417 and multiple first piezoelectric regions 416 are patterned in the first etching step and therefore have the same shape; for example, after the multiple upper electrode regions 417 and the first piezoelectric regions 416 are patterned, the lower electrode region 415 is patterned in a separate etching step and includes multiple actuation portions 415A and multiple detection portions 415B (each detection portion is in...). Figure 16A (See image) and multiple electrical connection portions 415C. Specifically, each of the multiple actuation portions 415A is generally located below the corresponding upper electrode region 417 and the first piezoelectric region 416; each detection portion 415B is located only on one side, particularly in… Figure 16A Extending laterally to the right relative to the plurality of upper electrode regions 417 and the first piezoelectric region 416; and each electrical connection portion 415C particularly in Figure 16A It extends laterally on both sides of the upper electrode region 417 and the first piezoelectric region 416.

[0134] Each actuation portion 415A of the lower electrode region 415, each first piezoelectric region 416, and each upper electrode region 417 respectively form the lower actuation electrode 81, the piezoelectric actuation region 82, and the upper actuation electrode 83 of each actuation structure 80.

[0135] especially, Figure 16A and Figure 16B The first set of actuation structures 80A is shown (at the corresponding first lower forming region 407), and Figure 16B Two second-group actuation structures 80B are shown, and these two second-group actuation structures are in Figure 4A The actuator 50 is adjacent to the first set of actuation structures 80A in the radial direction.

[0136] Subsequently, Figure 17A and Figure 17B In this process, for example, a piezoelectric layer 423 made of aluminum nitride (AlN) and having a thickness in the range of 0.5-3 μm, particularly 1 μm, is deposited on the front side of the wafer 400 and patterned by photolithography and selective etching to form a plurality of second piezoelectric regions 430 (in Figure 17A (Only one is visible in the middle) and multiple passivation regions 431.

[0137] Each passivation region 431 surrounds the corresponding actuation structure 80, and is located in a portion of the electrical connection portion 415C of the lower electrode region 415. Figure 17A On the and a portion of the second insulating layer 412 ( Figure 17B Extending upwards, and forming a plurality of first openings 432, each covering the corresponding upper electrode region 417.

[0138] The second piezoelectric regions 430 each extend above the corresponding detection portion 415B of the lower electrode region 415 and are a certain distance away from the corresponding passivation region 431.

[0139] Subsequently, in 18A and Figure 18B In this process, a third conductive layer 424, made of, for example, molybdenum, platinum, yttrium, or iridium oxide, is deposited and patterned on the wafer 400 (on the front side of the wafer 400) to form first, second, and third conductive connection regions 435-437 and upper detection electrode region 438, as described below.

[0140] In detail, the first and second conductive connection regions 435 and 436 extend above the first and second sets of actuation structures 80A and 80B within the plurality of first openings 432, respectively, contact the corresponding upper electrode region 417, and extend above the corresponding passivation region 431.

[0141] Furthermore, in this embodiment, portions of the first and second conductive connection regions 435, 436 extend onto each actuation structure 80 on the second insulating layer 412. Figure 18B On the sides of the piezoelectric actuator 50, piezoelectric actuators 50 are formed respectively. Figure 2A The first and second conductive tracks 89A and 89B of the piezoelectric actuator 50. In particular, the first conductive connection region 435 interconnects the first set of actuation structures 80A and connects to the first set of upper electrode pads 90A, and the second conductive connection region 436 interconnects the second set of actuation structures 80B and connects to the second set of upper electrode pads 90B of the piezoelectric actuator 50.

[0142] The upper detection electrode region 438 extends above each second piezoelectric region 430 and corresponds to... Figure 2A The third conductive track 95 and the third conductive connection region 437 extending above the second insulating layer 412 are in direct electrical contact so as to electrically connect to the third conductive track 95. Figure 2A The corresponding test pad 96 is shown in the figure.

[0143] In fact, each detection portion 415B of the lower electrode region 415, each second piezoelectric region 430 and each upper detection electrode region 438 respectively form the lower detection electrode 92, piezoelectric detection region 93 and upper detection electrode 94 of each deformation sensor 91 (here, as described above, each deformable ring 55 has a deformation sensor).

[0144] Subsequently, in 19A and Figure 19B In this process, selective etching is performed on the front side of the wafer 400 to form trenches 445 extending through the second insulating layer 412 and the structural layer 411. Specifically, in Figure 19BIn the middle, two grooves 445 can be seen, which extend to the left side of the first set of actuation structures 80A, between the first and second sets of actuation structures 80A and 80B, and to the right side of the second set of actuation structures 80B.

[0145] In detail, the groove 445 can be used to separate the deformable rings 55 from each other and to connect with the movable central portion 56. Figure 2A (separate, as described below.)

[0146] In addition, refer to again Figure 19A and Figure 19B The second forming layer 450 is deposited on the second surface 405B of the working substrate 405 and is photolithographically patterned to form a window 451 on the back side of the wafer 400, located below the actuation structure 80, the deformation sensor 91, and the second lower forming region 408.

[0147] Subsequently, Figure 20A and Figure 20B In this process, starting from the second surface 405B of the working substrate 405, the wafer 400 is selectively etched, for example by dry chemical etching, to remove semiconductor material from the wafer at window 451. Furthermore, portions of the reinforcing layer 409 not covered by the first underforming region 407 and the plurality of second underforming regions 408 are removed. Thus, a working cavity 452 corresponding to the cavity 52 of the piezoelectric actuator 50 is formed. Therefore, a support portion 405' corresponding to the substrate 57 of the piezoelectric actuator 50 is retained from the working substrate 405, and a central portion 409' and a plurality of connecting portions 409 are retained from the reinforcing layer 409.

[0148] Then, the second forming layer 450 is used again as an etching mask to remove portions of the first lower forming region 407, the plurality of second lower forming regions 408, and the first insulating layer 410, specifically the central portion 409' of the reinforcing layer 409 and the sides of the plurality of connecting portions 409"". In this way, the trench 445 becomes a through trench. Figure 21B .

[0149] Then remove the second forming layer 450.

[0150] like Figure 21A and Figure 21BAs shown, the central portion 409' of the reinforcing layer 409 and the remaining portion (denoted by 410') of the first insulating layer 410 form the opening / closing structure 86; the plurality of connecting portions 409" of the reinforcing layer 409 and the remaining portion (denoted by 410") of the first insulating layer 410 form the reinforcing structure 85. Furthermore, the structural layer 411 and the second insulating layer 412 on the side of the working cavity 452, together with the support portion 405' of the substrate 405, form a frame 53, and connecting portions 60, 65, 70, 75, a movable central portion 56, and deformable rings 55A-55C are formed on the working cavity 452. Figure 21B The middle part is marked with a dashed line.

[0151] Finally, the wafer 400 is diced, and after the usual electrical connection and packaging steps, each die is formed. Figure 2A The piezoelectric actuator 50 shown is illustrated.

[0152] In this process, the passivation region 431 is made of, for example, aluminum nitride. Indeed, aluminum nitride possesses excellent electrical insulation properties and is chemically stable in oxidizing environments such as air and humidity, as well as at high temperatures (even up to 1077°C). Therefore, the passivation region 431 allows for the passivation of the piezoelectric actuator 50 by depositing and patterning a single layer of material, thereby reducing the manufacturing steps and cost of the piezoelectric actuator 50 itself.

[0153] Finally, it is clear that modifications and alterations may be made to the piezoelectric actuators 50, 280 and the manufacturing methods described and illustrated herein without departing from the scope of this disclosure as defined in the appended claims.

[0154] For example, the manufacturing method described herein can be adapted to manufacture the piezoelectric actuator 280 in a manner readily apparent to those skilled in the art, for example by forming only the lower forming region, which can be used to obtain the reinforcing structure 85, starting from the first forming layer 406.

[0155] Obviously, the number of deformable rings, actuation structures, and deformation sensors can be modified based on the specific application.

[0156] In addition, deformation sensors can be arranged on one or more deformable rings.

[0157] Depending on the deformation and the desired application, the layers forming the deformable structure 54 can have different thicknesses.

[0158] In addition, fluid channels can have different shapes.

[0159] For example, the bias and measurement circuitry can be formed in the same die as the piezoelectric actuator.

[0160] Control units 220 and 320 may be integrated into piezoelectric actuators 50 and 280 or into body 205, or formed from independent devices such as ASICs.

[0161] Furthermore, the lower actuation electrode and the lower detection electrode can be formed from different conductive regions.

[0162] At least one embodiment of this disclosure relates to a MEMS actuator (50; 280) comprising: a body (51) surrounding a cavity (52); a deformable structure (54) suspended on the cavity and including a movable portion (56) and a plurality of deformable elements (55) arranged sequentially to each other, the deformable elements connecting the movable portion to the body and each subjecting to deformation; and at least one set of a plurality of actuation structures (80A, 80B) supported by the deformable elements (55) and configured such that the translation of the movable portion is greater than the deformation of each deformable element (55), each actuation structure including a corresponding first piezoelectric region (82).

[0163] In some embodiments, the deformable structure (54) is integral, substantially planar, and includes a semiconductor material layer (411), wherein the movable portion (56) and the deformable element (55) are adjacent structures having an upper surface in a plane when at rest.

[0164] In some embodiments, the deformable element (55) has a generally annular shape and surrounds the movable portion (56); the at least one set of plurality of actuating structures is a first plurality of actuating structures (80A) configured to deform the deformable structure (54) and move the movable portion (56) along a first direction; the actuator further includes a second plurality of actuating structures (80B), each of the second plurality of actuating structures including a corresponding piezoelectric region equal to the first piezoelectric region (83), the second plurality of actuating structures being configured to deform the deformable structure (54) and move the movable portion (56) along a second direction.

[0165] In some embodiments, the actuation structures in the first and second plurality of actuation structures (80A, 80B) are alternately and continuously arranged in each deformable element (55), and wherein the deformable structure (54) includes a plurality of arms (60, 65, 70, 75); a first arm (60) of the plurality of arms extends between the body (51) and the plurality of deformable elements; a second arm (65, 70) of the plurality of arms extends between adjacent deformable elements; and a third arm (75) of the plurality of arms extends between the plurality of deformable elements and the movable portion (56), wherein the second arm (65, 70) couples the actuation structure of the first plurality of actuation structures on the deformable element to the actuation structure of the second plurality of actuation structures on the adjacent deformable element.

[0166] In some embodiments, the deformable structure further includes a plurality of reinforcing structures (85) supported by the deformable element (55) on opposite sides of the actuating structure in the first plurality of actuating structures (80A), each reinforcing structure being arranged at the central portion of a corresponding actuating structure in the first plurality of actuating structures (80A) and integrated with a corresponding arm in the plurality of arms.

[0167] In some embodiments, the plurality of deformable elements (55) includes a plurality of concentric rings, and the actuation structure in the first and second plurality of actuation structures (80A, 80B) is formed by piezoelectric strips extending circumferentially at uniform distances from each other on each deformable element, each piezoelectric strip defining a curved centerline having a center (C), wherein each arm (60, 65, 70, 75) is radially aligned with the center of the actuation structure in the second plurality of actuation structures (80B) placed on the first deformable element of the plurality of deformable elements (55) and with the center of the actuation structure in the first plurality of actuation structures (80A) placed on the second deformable element of the plurality of deformable elements, the second deformable element being adjacent to the first deformable element and inside the first deformable element.

[0168] In some embodiments, the movable portion (56) is formed by a platform, and the deformable structure (54) includes an opening / closing structure (86) formed by a region protruding from the movable portion (56).

[0169] In some embodiments, at least one detection structure (91) is supported by the deformable structure (54) and configured to detect deformation of the deformable structure, each detection structure including a corresponding second piezoelectric region (93).

[0170] In some embodiments, each of the at least one plurality of actuation structures (80A, 80B) includes a corresponding first region stack, the first region stack including a lower actuation electrode (81), a first piezoelectric region (82) and an upper actuation electrode (83), and the at least one detection structure (91) includes a corresponding second region stack, the second region stack including a lower detection electrode (92), a second piezoelectric region (93) and an upper detection electrode (94), wherein the lower detection electrode (92) of each detection structure (91) and the lower actuation electrode (81) of each actuation structure are formed by a single conductive region.

[0171] In some embodiments, a plurality of passivation regions (431) are provided, each passivation region surrounding a corresponding actuation structure in the at least one set of plurality of actuation structures (80A, 80B) and formed of the same material as the second piezoelectric region (93).

[0172] At least one embodiment of this disclosure relates to a flow regulator actuator (200; 250; 270), comprising: a channel body (205; 255); a fluid channel (210; 260) extending within the channel body and having an end portion; a MEMS actuator according to any one of claims 8-10, wherein the movable portion (56) faces the end portion and is configured to change the cross-section of a passage disposed between the end portion and the movable portion; and a control unit (220) coupled to the MEMS actuator and configured to provide a bias voltage to the at least one set of plurality of actuation structures (80A, 80B) and receive a detection voltage from the at least one detection structure (91).

[0173] In some embodiments, the end portion of the fluid channel is in contact with the movable portion (56) when at rest.

[0174] In some embodiments, the end portion of the fluid channel is at a distance from the movable portion (56) when at rest and forms a fluid passage (265; 285) with the movable portion.

[0175] At least one embodiment of this disclosure relates to a loudspeaker (300) comprising: a housing (303) defining a cavity (305); a diaphragm (306) attached to the housing and suspended over the cavity; a MEMS actuator according to any one of claims 8-10, wherein the deformable structure (54) is coupled to the diaphragm and configured to cause deformation of the diaphragm; and a control unit (320) coupled to the MEMS actuator and configured to provide a bias voltage to the at least one set of plurality of actuation structures (80A, 80B) and receive a detection voltage from the at least one detection structure (91).

[0176] At least one embodiment of the present invention relates to a method for actuating an embodiment of a MEMS actuator of the present disclosure, comprising the steps of: providing a first bias voltage to a first plurality of actuation structures (80A) by a control unit and not providing any bias voltage to a second plurality of actuation structures (80B) to cause partial deformation of a portion of the deformable element (55) and translation of a movable portion (56) along a first direction, the portion supporting an actuation structure in the first plurality of actuation structures; providing a second bias voltage to the second plurality of actuation structures (80B) by the control unit and not providing any bias voltage to the first plurality of actuation structures (80A) to cause partial deformation of a portion of the deformable element (55) and translation of the movable portion along a second direction opposite to the first direction, the portion supporting an actuation structure in the second plurality of actuation structures.

[0177] At least one embodiment of this disclosure relates to a method of manufacturing an embodiment of a MEMS actuator of this disclosure, comprising the steps of: forming cavities (452, 52) in a working substrate (405) of a semiconductor material wafer (400) to define a deformable structure (54) suspended on the cavity and a frame portion (53) surrounding the suspension structure; defining the deformable structure (54) to form a movable portion (56) and a plurality of deformable elements (55), the plurality of deformable elements being arranged sequentially on each other and connecting the movable portion to the frame portion and each deformable element being deformed; and forming at least one set of a plurality of actuation structures (80A, 80B) on the deformable elements (55), each actuation structure including a corresponding first piezoelectric region (82).

[0178] In some embodiments of the method for manufacturing the MEMS actuator of this disclosure, a cavity may be formed in a working substrate, including the steps of: forming a plurality of shaped regions (407, 408) on a first surface (405A) of the working substrate (405); forming a reinforcing layer (409) and a structural layer (411) on the plurality of shaped regions; forming a plurality of trenches (445) in the structural layer; and selectively removing the substrate from a second surface (405B) opposite to the first surface down to the structural layer, thereby forming the cavity, a plurality of reinforcing structures (85), the deformable structure (54), and an opening / closing structure (86) protruding from the structural layer toward the cavity.

[0179] In some embodiments of the method for manufacturing the MEMS actuator of this disclosure, the step of forming at least one detection structure (91) on the deformable element may be included, each of the at least one detection structure including a corresponding second piezoelectric region (93).

[0180] In some embodiments of the method for manufacturing the MEMS actuator of this disclosure, forming at least one set of multiple actuation structures may be included, including: forming multiple lower actuation electrode regions (81) from a first conductive layer (420); forming multiple first piezoelectric regions (82) from a first piezoelectric layer (421), each first piezoelectric region on a corresponding lower actuation electrode region; and forming multiple upper actuation electrode regions (83) from a second conductive layer (422), each upper actuation electrode region on a corresponding first piezoelectric region; and forming the at least one detection structure includes: forming at least one lower detection electrode region (92) from the first conductive layer (420); forming a corresponding second piezoelectric region (93) from a second piezoelectric layer (423) on the at least one lower detection electrode region; and forming at least one upper detection electrode region (94) from a third conductive layer (424), each upper detection electrode region on a corresponding second piezoelectric region.

[0181] In some embodiments of the method for manufacturing the MEMS actuator of the present disclosure, the method may include forming a corresponding second piezoelectric region, including depositing a second piezoelectric layer (423) and patterning the second piezoelectric layer to form a corresponding second piezoelectric region (93), and forming a plurality of passivation regions (431), each passivation region surrounding a corresponding actuation structure (80A, 80B) belonging to the at least one set of a plurality of actuation structures.

[0182] The various embodiments described above can be combined to provide other embodiments. If desired, aspects of the embodiments can be modified to incorporate concepts from various patents, applications, and publications to provide other embodiments.

[0183] Based on the detailed description above, these and other changes can be made to the embodiments. Generally, the terminology used in the appended claims should not be construed as limiting the claims to the specific embodiments disclosed in the specification and claims, but should be interpreted to include all possible embodiments and the full scope of equivalents granted by these claims. Therefore, the claims are not limited to this disclosure.

Claims

1. A MEMS actuator, comprising: a body surrounding a cavity; a deformable structure suspended over the cavity, the deformable structure comprising: a movable portion; a plurality of deformable elements arranged in series, the plurality of deformable elements connecting the movable portion to the body and each deformable element being subject to deformation; at least one set of a plurality of actuation structures supported by the deformable elements, the at least one set of a plurality of actuation structures being configured to cause a translation of the movable portion that is greater than a deformation of each of the plurality of deformable elements, each of the actuation structures comprising a respective first piezoelectric region, wherein the first piezoelectric region is a thin film piezoelectric layer; wherein: the deformable elements have a substantially annular shape and surround the movable portion; the at least one set of a plurality of actuation structures is a first plurality of actuation structures, the first plurality of actuation structures being configured to deform the deformable structure and move the movable portion in a first direction; and the MEMS actuator further comprises a second plurality of actuation structures, each of the second plurality of actuation structures comprising a respective piezoelectric region equal to the first piezoelectric region, the second plurality of actuation structures being configured to deform the deformable structure and move the movable portion in a second direction opposite to the first direction; and actuation structures of the first plurality of actuation structures and the second plurality of actuation structures are arranged in series on each of the deformable elements; wherein the deformable structure comprises a plurality of arms, a first arm of the plurality of arms extends between the body and the plurality of deformable elements, a second arm of the plurality of arms extends between adjacent deformable elements of the plurality of deformable elements, a third arm of the plurality of arms extends between the plurality of deformable elements and the movable portion, wherein the second arm couples an actuation structure of the first plurality of actuation structures on the deformable element to an actuation structure of the second plurality of actuation structures on the adjacent deformable element; and wherein the deformable structure further comprises a plurality of reinforcement structures supported by the deformable elements on opposite sides with respect to actuation structures of the first plurality of actuation structures, each reinforcement structure is arranged at a central portion of a respective actuation structure of the first plurality of actuation structures and is integrated with a respective one of the plurality of arms.

2. The MEMS actuator of claim 1, wherein: the deformable structure is monolithic, substantially planar, and comprises a layer of semiconductor material; the movable portion is adjacent to the plurality of deformable elements; and the movable portion comprises a first surface and each of the plurality of deformable elements comprises a second surface, and the first surface and the second surface are aligned in a plane when the movable portion and the plurality of deformable elements are at rest.

3. The MEMS actuator of claim 1 or 2, wherein: the plurality of deformable elements comprises a plurality of concentric rings; and the plurality of arms comprises a plurality of spokes. ​ The actuation structures in the first plurality of actuation structures and in the second plurality of actuation structures are formed by piezoelectric strips extending on each deformable element at a uniform distance from each other and annularly, each piezoelectric strip defining a curved midline having a center; and Each arm in the plurality of arms is radially aligned with the center of one actuation structure in the second plurality of actuation structures placed on a first deformable element in the plurality of deformable elements, and radially aligned with the center of one actuation structure in the first plurality of actuation structures placed on a second deformable element in the plurality of deformable elements, the second deformable element being adjacent to the first deformable element and surrounded by the first deformable element.

4. The MEMS actuator of claim 1 or 2, wherein the movable portion is a platform on and overlapping the cavity; and the deformable structure comprises a shutter structure having a region protruding from the movable portion.

5. The MEMS actuator of claim 1, further comprising at least one detection structure on the deformable structure, and wherein the at least one detection structure is configured to detect the deformation of the deformable structure, and the at least one detection structure comprises a respective second piezoelectric region.

6. The MEMS actuator of claim 5, wherein: each actuation structure in the at least one set of plurality of actuation structures comprises a respective first region stack comprising a lower actuation electrode, a first piezoelectric region, and an upper actuation electrode; and the at least one detection structure comprises a respective second region stack comprising a lower detection electrode, a second piezoelectric region, and an upper detection electrode.

7. The MEMS actuator of claim 6, further comprising a plurality of passivation regions, each passivation region surrounding a respective actuation structure in the at least one set of plurality of actuation structures.

8. A flow regulator comprising: a channel body; a fluid channel extending in the channel body and having an end portion; a passage cross-section adjacent to the end portion; a MEMS actuator according to any one of claims 5-7, wherein the movable portion faces the end portion and is configured to change the passage cross-section arranged between the end portion and the movable portion; a control unit coupled to the MEMS actuator, the control unit being configured to provide a bias voltage to the at least one set of plurality of actuation structures and to receive a detection voltage from the at least one detection structure.

9. The flow regulator of claim 8, wherein the end portion of the fluid channel is in contact with the movable portion when the movable portion is in a rest position.

10. The flow regulator of claim 8, wherein, The end portion of the fluid channel is spaced apart from the movable portion by a fluid passage when the movable portion is in a rest position.

11. A loudspeaker comprising: a housing bounding a first cavity; a diaphragm attached to the housing and on the cavity; a MEMS actuator according to any one of claims 1-10. The MEMS actuator of any one of claims 5-7, wherein the deformable structure is coupled to the diaphragm and configured to cause deformation of the diaphragm. a control unit coupled to the MEMS actuator and configured to provide a bias voltage to the at least one set of multiple actuation structures and to receive a detection voltage from the at least one detection structure.

12. A method of manufacturing a MEMS actuator, comprising: forming a cavity in a substrate, defining a deformable structure suspended over the cavity and a frame portion surrounding the deformable structure; defining the deformable structure to form a movable portion and a plurality of deformable elements arranged in series, the plurality of deformable elements connecting the movable portion to the frame portion, and each deformable element being subject to deformation; and forming at least one set of multiple actuation structures over the deformable elements, each of the actuation structures comprising a respective first piezoelectric region, wherein the first piezoelectric region is a thin film piezoelectric layer; wherein: the deformable elements have a substantially annular shape and surround the movable portion; the at least one set of multiple actuation structures is a first set of multiple actuation structures configured to deform the deformable structure and move the movable portion in a first direction; the method further comprises: forming a second set of multiple actuation structures, each of the second set of multiple actuation structures comprising a respective piezoelectric region equal to the first piezoelectric region, the second set of multiple actuation structures configured to deform the deformable structure and move the movable portion in a second direction opposite to the first direction, wherein actuation structures of the first set of multiple actuation structures and the second set of multiple actuation structures are arranged in series on each of the deformable elements, forming a plurality of arms of the deformable structure, a first arm of the plurality of arms extending between the frame portion and the plurality of deformable elements; a second arm of the plurality of arms extending between adjacent deformable elements of the plurality of deformable elements, a third arm of the plurality of arms extending between the plurality of deformable elements and the movable portion, wherein the second arm couples an actuation structure of the first set of multiple actuation structures on the deformable element to an actuation structure of the second set of multiple actuation structures on an adjacent deformable element; and forming a plurality of reinforcement structures supported by the deformable elements on opposite sides with respect to the actuation structures of the first set of multiple actuation structures, each reinforcement structure being arranged at a central portion of a respective actuation structure of the first set of multiple actuation structures and integrated with a respective one of the plurality of arms.

13. The method of claim 12, wherein forming the cavity further comprises: forming a plurality of shaped regions on a first surface of the substrate; forming a reinforcement layer and a structure layer on the plurality of shaped regions; forming a plurality of trenches in the structure layer; and selectively removing portions extending from the second surface of the substrate to the structural layer, wherein selectively removing the portions forms the cavity, a plurality of stiffening structures, the deformable structure, and an shutter structure protruding from the structural layer toward the cavity.

14. The method of claim 12, further comprising forming at least one detection structure on the deformable element, the at least one detection structure comprising a respective second piezoelectric region.

15. The method of claim 14, wherein: forming the at least one set of a plurality of actuation structures comprises: forming a plurality of lower actuation electrode regions from a first conductive layer; forming a plurality of first piezoelectric regions from a first piezoelectric layer, the plurality of first piezoelectric regions on a respective one of the lower actuation electrode regions; and forming a plurality of upper actuation electrode regions from a second conductive layer, the plurality of upper actuation electrode regions on a respective one of the first piezoelectric regions; and forming at least one detection structure comprises: forming a lower detection electrode region from the first conductive layer; forming a respective second piezoelectric region from a second piezoelectric layer, the second piezoelectric region on the lower detection electrode region; and forming an upper detection electrode region from a third conductive layer, the upper detection electrode region on the respective second piezoelectric region.

16. The method of claim 15, wherein forming each actuation structure of the plurality of actuation structures comprises: depositing and patterning the second piezoelectric layer to form the respective second piezoelectric region; and surrounding a respective actuation structure of the at least one set of a plurality of actuation structures with a respective passivation region formed on a corresponding one of the respective second piezoelectric regions.

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