阅读说明：本技术 具有非共面致动和位移的显微机械加工的超声换能器 (Micromachined ultrasonic transducer with non-coplanar actuation and displacement ) 是由 R·巴德翰罗伊 弗雷德里克·兰泰里 爱德华·达克鲁兹 弗拉维安·达洛兹 J·F·热利 于 2021-04-30 设计创作，主要内容包括：本发明提供了一种具有非共面致动和位移的显微机械加工的超声换能器,该显微机械加工的超声换能器包括：板,该板具有突出的中心质量块；基底,该基底具有被配置为接纳中心质量块的中心凹入部；第一电极,该第一电极耦接到中心质量块的非水平边缘表面；以及第二电极,该第二电极耦接到中心凹入部的非水平边缘表面。板可至少沿板和基底的外周边区域耦接到基底。(The present invention provides a micromachined ultrasonic transducer with non-coplanar actuation and displacement, the micromachined ultrasonic transducer comprising: a plate having a protruding central mass; a base having a central recess configured to receive the central mass; a first electrode coupled to a non-horizontal edge surface of the central mass; and a second electrode coupled to the non-horizontal edge surface of the central depression. The plate may be coupled to the substrate at least along an outer peripheral region of the plate and the substrate.)

1. A capacitive transducer comprising:

a plate comprising a protruding central mass;

a base having a central recess configured to receive the central mass;

a first electrode coupled to a non-horizontal edge surface of the central mass; and

a second electrode coupled to a non-horizontal edge surface of the central depression,

wherein the plate is coupled to the substrate at least along the plate and an outer peripheral region of the substrate.

2. A capacitive transducer according to claim 1, wherein the non-horizontal edge surfaces of the central mass and the central recess are substantially vertical surfaces.

3. A capacitive transducer according to claim 1, wherein the non-horizontal edge surface of the central mass and the non-horizontal edge surface of the central recess are angled surfaces.

4. A capacitive transducer according to claim 1, wherein the non-horizontal edge surfaces of the central mass and the central recess are rounded surfaces.

5. A capacitive transducer according to claim 1, wherein the non-horizontal edge surfaces of the central mass and the central recess are corrugated surfaces.

6. A capacitive transducer according to claim 1, wherein at least a portion of the top surface of the central mass is non-coplanar with a portion of the top surface of the plate that is not the central mass.

7. A capacitive transducer according to claim 1, wherein substantially the entire top surface of the substrate is coupled to the corresponding bottom surface of the plate.

8. The capacitive transducer of claim 1, wherein:

a first vertical gap exists between a bottom surface of the central mass and a bottom surface of the central recess;

a second vertical gap exists between the non-central proof-mass portion of the plate and the top surface of the base;

a horizontal gap exists between the first electrode and the second electrode.

9. A capacitive transducer according to claim 8, wherein the first vertical gap is equal to the second vertical gap.

10. A capacitive transducer according to claim 8, wherein the horizontal gap is equal to one or both of the first vertical gap and the second vertical gap.

11. A capacitive transducer according to claim 8, wherein the first vertical gap, the second vertical gap and the horizontal gap are filled with a gas.

12. A capacitive transducer according to claim 8, wherein the first vertical gap, the second vertical gap and the horizontal gap are filled with air.

13. A capacitive transducer according to claim 8, wherein the plate and the substrate are configured to couple to form an airtight barrier around the gap.

14. A capacitive transducer according to claim 13, wherein the first vertical gap, the second vertical gap and the horizontal gap comprise a substantially gas-free vacuum.

15. A capacitive transducer comprising:

a plate comprising a protruding central mass;

a base having a central recess configured to receive the central mass;

a first electrode coupled to a non-horizontal edge surface of the central mass; and

a second electrode coupled to a non-horizontal edge surface of the central depression,

wherein:

the plate is coupled to the substrate at least along an outer peripheral region of the plate and the substrate,

the non-horizontal edge surfaces of the central mass and the non-horizontal edge surfaces of the central recess are substantially vertical surfaces,

a first vertical gap exists between a bottom surface of the central mass and a bottom surface of the central recess,

a second vertical gap exists between the non-central proof-mass portion of the plate and the top surface of the base; and is

A horizontal gap exists between the first electrode and the second electrode.

16. A capacitive transducer according to claim 15, wherein at least a portion of the top surface of the central mass is non-coplanar with a portion of the top surface of the plate that is not the central mass.

17. A capacitive transducer according to claim 15, wherein substantially the entire top surface of the substrate is coupled to the corresponding bottom surface of the plate.

18. A capacitive transducer according to claim 15, wherein the horizontal gap is equal to one or both of the first vertical gap and the second vertical gap.

19. A capacitive transducer comprising:

a plate comprising a protruding central mass;

a base having a central recess configured to receive the central mass;

a first electrode coupled to a non-horizontal edge surface of the central mass; and

a second electrode coupled to a non-horizontal edge surface of the central depression,

wherein:

the plate is coupled to the substrate at least along an outer peripheral region of the plate and the substrate,

the non-horizontal edge surfaces of the central mass and the central recess are substantially vertical surfaces, and

at least a portion of the top surface of the central mass is non-coplanar with a portion of the top surface of the plate that is not the central mass.

20. A capacitive transducer according to claim 19, wherein substantially the entire top surface of the substrate is coupled to the corresponding bottom surface of the plate.

Technical Field

Certain embodiments relate to transducers. More particularly, certain embodiments relate to micromachined ultrasonic transducers with non-coplanar actuation and displacement.

Background

Ultrasound devices can be used to image objects such as organs and soft tissue in the human body as well as non-human objects. For example, in addition to ultrasound imaging of humans, animals, etc., ultrasound devices may also be used to apply applications such as ultrasound/acoustic sensing, non-destructive evaluation (NDE), ultrasound therapy (e.g., High Intensity Focused Ultrasound (HIFU)), and the like.

Ultrasound devices may use real-time, non-invasive high frequency sound waves to produce a series of two-dimensional (2D) images and/or three-dimensional (3D) images. The acoustic wave may be transmitted by a transmitting transducer and a reflection of the transmitted acoustic wave may be received by a receiving transducer. The received sound waves may then be processed to display an image of the target. Conventional Capacitive Micromachined Ultrasonic Transducers (CMUTs) used as transmitting transducers and/or receiving transducers may include a top electrode and a bottom electrode, wherein the top electrode may be moved by an electrical signal used to generate an acoustic wave or by receiving an acoustic wave used to generate an electrical signal that may be processed. The top and bottom electrodes may be separated by a gap, wherein the gap may comprise a degree of vacuum or the gap may be filled with, for example, air.

Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present disclosure as set forth in the remainder of the present application with reference to the drawings.

Disclosure of Invention

The present invention provides a system and/or method for a micromachined ultrasonic transducer with non-coplanar actuation and displacement, substantially as shown in and/or described in connection with at least one of the figures, as set forth more completely in the claims.

These and other advantages, aspects, and novel features of the present disclosure, as well as details of an illustrated embodiment thereof, will be more fully understood from the following description and drawings.

Drawings

Fig. 1 is a block diagram of an exemplary ultrasound system that may be used for ultrasound imaging, in accordance with various embodiments.

Figure 2 illustrates a configuration of an exemplary Capacitive Micromachined Ultrasonic Transducer (CMUT) with non-coplanar actuation and displacement according to various embodiments.

Fig. 3 illustrates exemplary applicable dimensions of the exemplary CMUT of fig. 2 according to various embodiments.

Fig. 4 shows an exemplary graph of a simulation of displacement of an exemplary capacitive micromachined ultrasonic transducer, according to various embodiments.

Figure 5 illustrates another configuration of an exemplary Capacitive Micromachined Ultrasonic Transducer (CMUT) with non-coplanar actuation and displacement according to various embodiments.

Figure 6 illustrates another configuration of an exemplary Capacitive Micromachined Ultrasonic Transducer (CMUT) with non-coplanar actuation and displacement according to various embodiments.

Figure 7 illustrates another configuration of an exemplary Capacitive Micromachined Ultrasonic Transducer (CMUT) with non-coplanar actuation and displacement according to various embodiments.

Figure 8 illustrates another configuration of an exemplary Capacitive Micromachined Ultrasonic Transducer (CMUT) with non-coplanar actuation and displacement according to various embodiments.

Figure 9 illustrates another configuration of an exemplary Capacitive Micromachined Ultrasonic Transducer (CMUT) with non-coplanar actuation and displacement according to various embodiments.

Figure 10 illustrates another configuration of an exemplary Capacitive Micromachined Ultrasonic Transducer (CMUT) with non-coplanar actuation and displacement according to various embodiments.

Figure 11 illustrates another configuration of an exemplary Capacitive Micromachined Ultrasonic Transducer (CMUT) with non-coplanar actuation and displacement according to various embodiments.

Figure 12 illustrates another configuration of an exemplary Capacitive Micromachined Ultrasonic Transducer (CMUT) with non-coplanar actuation and displacement according to various embodiments.

Figure 13 illustrates another configuration of an exemplary Capacitive Micromachined Ultrasonic Transducer (CMUT) with non-coplanar actuation and displacement according to various embodiments.

Figure 14 illustrates another configuration of an exemplary Capacitive Micromachined Ultrasonic Transducer (CMUT) with non-coplanar actuation and displacement according to various embodiments.

Detailed Description

Certain embodiments may be found in micromachined ultrasonic transducers having non-coplanar actuation and displacement. Various embodiments of the present disclosure may use non-coplanar actuation and displacement, where actuation is via electrodes that are not coplanar with the membrane displacement direction.

Thus, various embodiments provide a technical effect of operation of a Capacitive Micromachined Ultrasonic Transducer (CMUT) in which electrodes used for actuation are not shorted to each other.

Although CMUTs may be used for medical imaging, in addition to ultrasound imaging of humans or animals, CMUTs may also be used for various other purposes, such as ultrasound/acoustic sensing, non-destructive evaluation (NDE), ultrasound therapy (e.g., High Intensity Focused Ultrasound (HIFU)), and the like.

The foregoing summary, as well as the following detailed description of certain embodiments, will be better understood when read in conjunction with the appended drawings. To the extent that the figures illustrate diagrams of the functional blocks of various embodiments, the functional blocks are not necessarily indicative of the division between hardware circuitry. It should be understood that the various embodiments are not limited to the arrangements and instrumentality shown in the drawings. It is to be understood that the embodiments may be combined, or that other embodiments may be utilized and that structural, logical, and electrical changes may be made without departing from the scope of the various embodiments. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims and their equivalents.

As used herein, an element or step recited in the singular and proceeded with the word "a" or "an" should be understood as not excluding plural said elements or steps, unless such exclusion is explicitly recited. Furthermore, references to "exemplary embodiments," "various embodiments," "certain embodiments," "representative embodiments," etc., are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Furthermore, unless explicitly stated to the contrary, embodiments "comprising," "including," or "having" an element or a plurality of elements having a particular property may include additional elements not having that property.

In addition, as used herein, the term "image" broadly refers to both a viewable image and data representing a viewable image. However, many embodiments generate (or are configured to generate) at least one viewable image. Further, as used herein, the phrase "image" is used to refer to ultrasound modes, such as B-mode (2D mode), M-mode, three-dimensional (3D) mode, CF mode, PW doppler, CW doppler, MGD, and/or sub-modes of B-mode and/or CF, such as Shear Wave Elastic Imaging (SWEI), TVI, Angio, B-flow, BMI _ Angio, and in some cases MM, CM, TVD, where "image" and/or "plane" includes a single beam or multiple beams.

Further, as used herein, the term processor or processing unit refers to any type of processing unit that can perform the required computations required by the various embodiments, such as single core or multi-core: a CPU, an Accelerated Processing Unit (APU), a graphics board, a DSP, an FPGA, an ASIC, or a combination thereof.

Additionally, it should be noted that the drawings may not depict objects to scale, but are presented in an effort to provide a clear explanation.

Fig. 1 is a block diagram of an exemplary ultrasound system that may be used for ultrasound imaging, in accordance with various embodiments. Referring to fig. 1, a block diagram of an exemplary ultrasound system 100 is shown. Ultrasound system 100 includes a transmitter 102, an ultrasound probe 104, a transmit beamformer 110, a receiver 118, a receive beamformer 120, an A/D converter 122, an RF processor 124, an RF/IQ buffer 126, a user input device 130, a signal processor 132, an image buffer 136, a display system 134, and an archive 138.

The transmitter 102 may comprise suitable logic, circuitry, interfaces and/or code that may be operable to drive the ultrasound probe 104. The ultrasound probe 104 may include, for example, a single element CMUT, a 1D array of CMUTs, a 2D array of CMUTs, a ring (ring) array of CMUTs, or the like. Thus, the ultrasound probe 104 may comprise a set of transducer elements 106, which may be, for example, CMUTs. In certain embodiments, the ultrasound probe 104 is operable to acquire ultrasound image data covering, for example, at least a substantial portion of an anatomical structure, such as a heart, a blood vessel, or any suitable anatomical structure. Each of the transducer elements 106 may be referred to as a channel.

The transmit beamformer 110 may comprise suitable logic, circuitry, interfaces and/or code that may be operable to control the transmitter 102 that drives the set of transmit transducer elements 106 to transmit ultrasonic transmit signals into a region of interest (e.g., a human, an animal, a subsurface cavity, a physical structure, etc.). The transmitted ultrasound signals may be backscattered from structures in the object of interest, such as blood cells or tissue, to generate echoes. The transducer elements 106 may then receive the echoes.

The set of transducer elements 106 in the ultrasound probe 104 is operable to convert the received echoes to analog signals and transmit to the receiver 118. The receiver 118 may comprise suitable logic, circuitry, interfaces and/or code that may be operable to receive signals from the ultrasound probe 104. The analog signals may be communicated to one or more of the plurality of a/D converters 122.

Thus, the ultrasound system 100 may be multiplexed such that ultrasound transmit signals are transmitted during certain time periods and echoes of these ultrasound signals are received during other time periods. Although not explicitly shown, various embodiments of the present disclosure may allow for the transmission of ultrasound signals and the reception of echoes from these signals to occur simultaneously. In such cases, the probe may include transmit transducer elements and receive transducer elements.

The plurality of a/D converters 122 may comprise suitable logic, circuitry, interfaces and/or code that may be operable to convert analog signals from the receiver 118 to corresponding digital signals. A plurality of a/D converters 122 are disposed between the receiver 118 and the RF processor 124. The present disclosure is not limited in this respect, though. Thus, in some embodiments, multiple a/D converters 122 may be integrated within receiver 118.

The RF processor 124 may comprise suitable logic, circuitry, interfaces and/or code that may be operable to demodulate digital signals output by the plurality of a/D converters 122. According to one embodiment, the RF processor 124 may include a complex demodulator (not shown) operable to demodulate the digital signals to form I/Q data pairs representative of corresponding echo signals. The RF data (which may be, for example, I/Q signal data, real-valued RF data, etc.) may then be passed to an RF/IQ buffer 126. The RF/IQ buffer 126 may comprise suitable logic, circuitry, interfaces and/or code that may be operable to provide temporary storage of RF or I/Q signal data generated by the RF processor 124.

Thus, various embodiments may enable, for example, the RF processor 124 to process real-valued RF data or any other equivalent representation of the data with an appropriate RF buffer 126.

The receive beamformer 120 may comprise suitable logic, circuitry, interfaces and/or code that may be operable to perform digital beamforming processing to, for example, sum delayed channel signals, phase shifted channel signals and/or weighted channel signals received from the RF processor 124 via the RF/IQ buffer 126 and output a beamformed signal. The delayed channel data, phase shifted channel data, and/or weighted channel data may be summed to form a scanline output from the receive beamformer 120, where the scanline may be, for example, complex or non-complex. The particular delay of the channel may be provided, for example, by the RF processor 124 or any other processor configured to perform this task. The delayed channel data, phase shifted channel data, and/or weighted channel data may be referred to as delay aligned channel data.

The resulting processed information may be a beam summation signal output from the receive beamformer 120 and communicated to the signal processor 132. According to some embodiments, the receiver 118, the plurality of a/D converters 122, the RF processor 124, and the beamformer 120 may be integrated into a single beamformer, which may be digital. In various embodiments, the ultrasound system 100 may include a plurality of receive beamformers 120.

The user input device 130 may be used to enter patient data, scan parameters, settings, select protocols and/or templates, etc. In an exemplary embodiment, the user input device 130 is operable to configure, manage and/or control the operation of one or more components and/or modules in the ultrasound system 100. In this regard, the user input device 130 may be used to configure, manage and/or control the operation of the transmitter 102, ultrasound probe 104, transmit beamformer 110, receiver 118, receive beamformer 120, RF processor 124, RF/IQ buffer 126, user input device 130, signal processor 132, image buffer 136, display system 134 and/or archive 138. The user input devices 130 may include switches, buttons, rotary encoders, touch screens, motion tracking, voice recognition, mouse devices, keyboards, cameras, and/or any other device capable of receiving user directions. In certain embodiments, for example, one or more of the user input devices 130 may be integrated into other components (such as the display system 134 or the ultrasound probe 104). For example, the user input device 130 may include a touch screen display.

The signal processor 132 may comprise suitable logic, circuitry, interfaces and/or code that may be operable to process the ultrasound scan data (i.e., the summed IQ signals) to generate an ultrasound image for presentation on the display system 134. The signal processor 132 is operable to perform one or more processing operations according to a plurality of selectable ultrasound modalities on the acquired ultrasound scan data. In an exemplary embodiment, the signal processor 132 may be used to perform display processing and/or control processing, and the like. As echo signals are received, acquired ultrasound scan data may be processed in real-time during a scan session. Additionally or alternatively, the ultrasound scan data may be temporarily stored in the RF/IQ buffer 126 during a scan session and processed in either an online operation or an offline operation. In various implementations, the processed image data may be presented at display system 134 and/or stored at archive 138. Archive 138 may be a local archive, Picture Archiving and Communication System (PACS), or any suitable device for storing images and related information.

The signal processor 132 may include one or more central processing units, microprocessors, microcontrollers, or the like. For example, the signal processor 132 may be an integrated component, or may be distributed in various locations. In an exemplary embodiment, the signal processor 132 may be capable of receiving input information from the user input device 130 and/or the profile 138, generating output that may be displayed by the display system 134, and manipulating the output in response to the input information from the user input device 130, and so forth. The signal processor 132 may be capable of performing, for example, any of the methods and/or sets of instructions discussed herein in accordance with various embodiments.

The ultrasound system 100 is operable to continuously acquire ultrasound scan data at a frame rate appropriate for the imaging situation in question. Typical frame rates may range from 20 to 120, but may be lower or higher. The acquired ultrasound scan data may be displayed on the display system 134 at the same frame rate, or at a slower or faster display rate. An image buffer 136 is included for storing processed frames of acquired ultrasound scan data that are not scheduled for immediate display. Preferably, the image buffer 136 has sufficient capacity to store at least several minutes of frames of ultrasound scan data. The frames of ultrasound scan data are stored in a manner that is easily retrievable therefrom according to their acquisition order or time. The image buffer 136 may be embodied as any known data storage medium.

Display system 134 may be any device capable of communicating visual information to a user. For example, the display system 134 may include a liquid crystal display, a light emitting diode display, and/or any suitable display or displays. The display system 134 may be operable to present ultrasound images and/or any suitable information.

The archive 138 may be one or more computer-readable memories, such as a Picture Archiving and Communication System (PACS), a server, a hard disk, a floppy disk, a CD-ROM, a DVD, a compact storage, a flash memory, a random access memory, a read-only memory, an electrically erasable and programmable read-only memory, and/or any suitable memory integrated with the ultrasound system 100 and/or communicatively coupled to the ultrasound system 100 (e.g., over a network). The archive 138 may include, for example, a database, library, information set, or other memory accessed by the signal processor 132 and/or incorporated into the signal processor 132. For example, the archive 138 can store data temporarily or permanently. The archive 138 may be capable of storing medical image data, data generated by the signal processor 132, and/or instructions readable by the signal processor 132, among others.

The components of the ultrasound system 100 may be implemented in software, hardware, firmware, etc. The various components of the ultrasound system 100 may be communicatively connected. The components of the ultrasound system 100 may be implemented separately and/or integrated in various forms. For example, the display system 134 and the user input device 130 may be integrated as a touch screen display. Additionally, although the ultrasound system 100 is described as including the receive beamformer 120, the RF processor 124, and the signal processor 132, various embodiments of the present disclosure may use a various number of processors. For example, various devices executing code may be generally referred to as processors. Various implementations may refer to each of these devices, including each of the RF processor 124 and the signal processor 132, as a processor. In addition, there may be other processors to additionally perform the tasks described as being performed by these devices including the receive beamformer 120, the RF processor 124 and the signal processor 132, and all of these processors may be referred to as "processors" for convenience of description.

Certain applications may wish to drive conventional Capacitive Micromachined Ultrasonic Transducers (CMUTs) that are sufficiently rigid such that they operate in a collapsed mode. That is, the top electrode is driven to the bottom electrode. This may permit the CMUT to provide a higher level of acoustic power, higher linearity, and wider bandwidth during operation. However, for conventional CMUTs having a top electrode and a bottom electrode, the top electrode may then contact the bottom electrode, causing an electrical short of the electrodes, which may cause permanent damage to the CMUT structure.

To avoid this problem, one or more isolation layers or bumps have been sandwiched between the bottom and top electrodes. However, charging problems due to trapped charges in the thin dielectric isolation layer may lead to electrical reliability problems. While various efforts have been made to overcome this problem, industrial CMUT devices have heretofore failed to overcome the problems associated with operating in the collapsed mode due to reliability issues. The two most important reasons for the generation of trapped charges are the manufacturing process of the CMUT, and the strong electric field in the gap during operation of the CMUT.

Charge may be trapped on the surface or within dielectric isolation layers that may be present in conventional CMUTs. Depending on the amplitude and frequency of the drive signal superimposed on the DC bias, the trapped charge shields the electrode surface with an unintended effect. In addition, such charges can cause problems during rapid retraction of the membrane after collapse.

While both academia and industry provide solutions including the use of PostCMUT, spacers (membrane bumps), extended edge insulator thickness, etc., these approaches only limit the charging problem to a smaller area. Charge trapping still occurs and therefore problems still exist.

Various embodiments of the present disclosure provide novel capacitive micromachined ultrasonic transducers in which actuation may be, for example, orthogonal to the direction of membrane vibration. In a conventional configuration, a bias and an AC signal are provided to electrodes attached to the membrane. Therefore, the electrode moves in the same direction with the displacement of the membrane, which directly causes collapse. The current structure and actuation process has the advantage of avoiding mechanical collapse even after traversing one-third of the gap height, thereby avoiding the collapse voltage constraints present in conventional CMUTs. Actuation may be achieved, for example, by applying a bias and an AC signal orthogonal to the direction of displacement.

Conventional Capacitive Micromachined Ultrasonic Transducers (CMUTs) include two plates separated by a vacuum or fluid gap. The plates are biased by a DC voltage and then superimposed with an AC signal having a selected frequency and amplitude. The operating principle of CMUTs is based on coulomb attraction law. During DC biasing, the electrostatic force and the mechanical restoring force balance each other, thereby holding the membrane at the target displacement position. However, at a certain DC bias voltage, the electrostatic force exceeds the restoring force and the membrane contacts the bottom electrode. For a fully clamped CMUT panel, this physical phenomenon occurs at about one third of the effective gap height. This distance is called the pull-in or collapse distance, and the voltage at which this occurs is called the collapse or pull-in voltage. One or more isolation layers may be sandwiched between the active film (top electrode), the gap (vacuum or fluid), and the back support structure (with bottom electrode) so that no short circuits occur during such collapse phenomena.

Collapse voltage V_colIs shown in the following equations 1 and 2:

wherein K is the membrane stiffness, ε₀Is the dielectric constant of free space, and a is the device area. The effective gap height is given by:

wherein g is₀Is a vacuum/air gap, t_rIs a high contact resistance layer thickness, and_ris the dielectric constant of the insulating material.

Thus, it can be seen that the bias voltage requirements (transmit pressure in transmit mode) of the CMUT, which primarily dominates the sensitivity of the device, can be controlled by varying the effective gap height, so that the other geometric parameters of the particular device are kept constant.

There are applications where the CMUT is used in the collapsed mode, however, in the conventional mode the collapse phenomenon does impose some constraints on the DC-shift after the pull-in level, especially when higher DC-broadening implies higher linearity and higher pressure during signal swing.

Figure 2 illustrates a configuration of an exemplary Capacitive Micromachined Ultrasonic Transducer (CMUT) with non-coplanar actuation and displacement according to various embodiments. Referring to fig. 2, there is shown a CMUT 200 comprising a plate 202 and a substrate 204. The plate 202 may include a central mass 203. The central mass 203 protrudes downward into a recess 205 in a corresponding region of the base 204. The substantially vertical edge of the central mass 203 comprises an electrode 210 and the substantially vertical edge of the recess 205 comprises an electrode 211. The electrodes 210 and 211 may be supplied with electric signals (DC bias and AC signal) for moving the plate 202 in the Z direction to generate an acoustic wave.

The plate 202 may be coupled to the substrate 204 at an outer peripheral region 202A of the plate 202. The coupling may be performed via any suitable method, including processes known in MEMS fabrication, such as wafer bonding.

As can be seen, CMUT 200 has an upper vertical gap 206A and a lower vertical gap 206B between plate 202 and substrate 204. There is also a horizontal gap 208 between electrode 210 and electrode 211. The horizontal gap 208 may be referred to as an electrode gap 208. Vertical gap 206A and vertical gap 206B are actuation boundaries that make the DC bias and AC signal orthogonal to the device displacement direction along the Z-axis. Although not shown, CMUT 200 may have a circular shape, a rectangular shape, or any other shape when viewed from the top at the X-Y plane.

Since the CMUT plate 202 has mechanical restraint in the X direction due to clamping at the edge (the outer peripheral region 202A of the plate 202), the degree of freedom of displacement may be mainly in the Z direction. Thus, even if the actuation is in the X direction, the X direction displacement may be much smaller than the Z direction displacement due to mechanical constraints. Various embodiments of the present disclosure may have a displacement ratio of, for example, 10 or more with respect to the relationship between Z-direction displacement and X-direction displacement. It may be noted that the displacement ratio may be determined for a particular use of CMUT 200.

Various parameters may be used to determine the displacement ratio. The displacement ratio may depend on various variables (e.g., the type of material used for the plate 202 and the substrate 204, the width of the peripheral edge 202A, etc.). Some dimensions that may be used to determine the displacement ratio are discussed with respect to fig. 3.

While an exemplary configuration is shown in fig. 2, as well as in other figures, it should be understood that the present disclosure allows for various other configurations that may also be used for CMUTs.

The substantially vertical edge may be referred to as a non-horizontal edge.

Fig. 3 illustrates exemplary applicable dimensions of the exemplary CMUT of fig. 2 according to various embodiments. Referring to fig. 3, a partial view of a CMUT 300 is shown which may be similar to CMUT 200. The displacement ratio may be used, for example, as the plate radius (P)_r)302, mass radius (M)_r)304 horizontal gap (G)_h)306, vertical gap (G)_v)307 and 309, mass thickness (M)_t)305 and plate thickness (P)_t)303. The horizontal gap 306 may be referred to as an electrode gap 306.

Vertical gap (G)_v)307 and 309 may be equal to each other. Vertical gap (G)_v)307 and/or 309 may be equal to the horizontal gap (G)_h)306. Vertical gap (G)_v)307 and/or 309 may be greater than the horizontal gap (G)_h)306. The various gaps may be measured in any suitable units, such as microns, nanometers, and the like.

The term "E_PI"may be an electrical pull-in voltage, or a DC bias required to collapse the electrodes toward each other in the X direction. The term "E_MC"can be used for the voltage required for mechanical collapse. Mechanical collapse is defined as the phenomenon when the central mass 203 contacts the bottom of the recess 205 of the substrate 204 under a certain DC bias.

Various embodiments of the present disclosure may convert ratio E_PI/E_MCTo be about, for example, 10 or more to allow full-swing mechanical Z-displacement. Since the conductive electrodes 210 are at the edges of the central mass 203, there may be no short circuit between the electrodes 210 and 211 even in the event of mechanical collapse. At E_PI/E_MCAt exemplary ratios of 10 or greater, it may not be desirable to have electro-engagement occur prior to mechanical collapse. Thus, it can be seen that the ratio of the horizontal gap to the vertical gap (G)_h/G_v) The electrical operating point of the CMUT may be defined. In addition, since the electrode 210 and the electrode 211 are less likely to be short-circuited, an isolation layer, which is generally used in the conventional CMUT structure, may not be required.

Fig. 4 shows an exemplary graph of a simulation of displacement of an exemplary capacitive micromachined ultrasonic transducer, according to various embodiments. Referring to fig. 4, a graph 400 is shown with DC bias in volts along the X-axis and normalized displacement along the Y-axis. Curve 402 shows the vertical gap (G) at various voltages_v)309, curve 404 shows the horizontal gap (G) at various voltages_h)306. The design parameters for the simulation were set to:

radius of plate (P)_r)302＝100um

Radius of mass (M)_r)304＝P_r/3

Vertical gap (G)_v)307 and 309 are 1 normalized units

Horizontal gap (G)_h)306＝G_v0.2 normalized Unit

Mass thickness (M)_t)305＝2*G_v

Plate thickness (P)_t)303＝1um

Based on the design parameters of the CMUT simulated in FIG. 4, the vertical gap (G)_v)307 and 309 are each 1 normalized unit, and the horizontal gap (G)_h)306 is 0.2 normalized units. As can be seen from curve 402 of graph 400, there is mechanical collapse, where a displacement of 1 normalized unit along the Z-axis occurs at slightly more than 90 volts. At the same voltage, it can be seen from curve 404 that the displacement of the edge of the central mass 203 is about 0.05 normalized units, much less than the horizontal gap of 0.2 normalized units.

Thus, it can be seen that the mechanical collapse without electrical pull-in clearly demonstrates the fact that full DC induced broadening can be achieved without the conventional pull-in related problems such as short circuits, dielectric charging, etc. Thus, various embodiments of the present disclosure may be used as a device that operates in collapse, and thus can provide wider bandwidth, increased linearity, and the like.

Figure 5 illustrates another configuration of an exemplary Capacitive Micromachined Ultrasonic Transducer (CMUT) with non-coplanar actuation and displacement according to various embodiments. Referring to fig. 5, there is shown a CMUT 500 similar to CMUT 200 except that the edge of the central mass 503 of the plate 502 is diagonal to the edge of the recess 505 of the base 504. Thus, the orientation of electrode 506 and electrode 507 is also diagonal. Diagonal edges may also be referred to as non-horizontal edges, where the tilt angle may be between 0 ° and 90 °. The orthogonal distance between electrode 506 and electrode 507 may be referred to as electrode gap 508.

Figure 6 illustrates another configuration of an exemplary Capacitive Micromachined Ultrasonic Transducer (CMUT) with non-coplanar actuation and displacement according to various embodiments. Referring to fig. 6, there is shown a CMUT 600 similar to CMUT 200 except that the edges of the central mass 603 and the edges of the recess 605 are corrugated. Thus, the electrode 606 and the electrode 607 are horizontally offset from the electrode 608 and the electrode 609. There is a horizontal gap 610 between electrode 606 and electrode 607 and between electrode 608 and electrode 609. The horizontal gap 610 may be referred to as an electrode gap 610.

A rippled edge may also be referred to as a non-horizontal edge.

Figure 7 illustrates another configuration of an exemplary Capacitive Micromachined Ultrasonic Transducer (CMUT) with non-coplanar actuation and displacement according to various embodiments. Referring to fig. 7, CMUT700 is similar to CMUT 200. CMUT700 includes a plate 702 having a central mass 703, and a base 704. Between the plate 702 and the substrate 704 there are an electrode 710 and an electrode 711 with a horizontal gap 708 and a vertical gap 706.

CMUT700 further includes a recess 703A in the center block 703. The specific dimensions of recess 703A may vary for various embodiments, and the shape of recess 703A may be any of a variety of shapes.

Figure 8 illustrates another configuration of an exemplary Capacitive Micromachined Ultrasonic Transducer (CMUT) with non-coplanar actuation and displacement according to various embodiments. Referring to fig. 8, CMUT800 is similar to CMUT 500. CMUT800 comprises a plate 802 with a central mass 803, and a base 804. Between the plate 802 and the substrate 804 there are electrodes 810 and 811 with horizontal 808 and vertical 806 gaps.

CMUT800 further comprises a recess 803A in the central mass 803. The specific dimensions of recess 803A may vary for various embodiments, and the shape of recess 803A may be any of a variety of shapes.

Figure 9 illustrates another configuration of an exemplary Capacitive Micromachined Ultrasonic Transducer (CMUT) with non-coplanar actuation and displacement according to various embodiments. Referring to fig. 9, CMUT900 is similar to CMUT 600. CMUT900 comprises a plate 902 with a central mass 903 and a base 904 with a recess 905. There are electrodes 906 and 907 with a horizontal gap 910 and electrodes 908 and 909 with a horizontal gap 910.

CMUT900 further comprises a recess 903A in the central mass 903. The specific dimensions of recess 903A may vary for various embodiments, and the shape of recess 903A may be any of a variety of shapes.

Figure 10 illustrates another configuration of an exemplary Capacitive Micromachined Ultrasonic Transducer (CMUT) with non-coplanar actuation and displacement according to various embodiments. Referring to fig. 10, CMUT 1000 is similar to CMUT 200 or CMUT700 except that plate 1002 is coupled to substrate 1004 such that substantially the entire top surface of substrate 1004 is coupled to the corresponding bottom surface of plate 1002. There may be a recess 1003A in the central mass 1003, where the specific dimensions of the recess 1003A may vary for various embodiments, and the shape of the recess 1003A may be any of a variety of shapes. Between the plate 1002 and the substrate 1004 there are an electrode 1010 and an electrode 1011 with a horizontal gap 1008 and a vertical gap 1006.

Figure 11 illustrates another configuration of an exemplary Capacitive Micromachined Ultrasonic Transducer (CMUT) with non-coplanar actuation and displacement according to various embodiments. Referring to fig. 11, CMUT 1100 is similar to CMUT 500 or CMUT 800. The CMUT 1100 comprises a plate 1102 with a central mass 1103 and a base 1104 with a recess 1105. Plate 1102 is coupled to substrate 1104 such that substantially the entire top surface of substrate 1104 is coupled to a corresponding bottom surface of plate 1102. There may be a recess 1103A in the central mass 1103, where the specific dimensions of the recess 1103A may vary for various embodiments, and the shape of the recess 1103A may be any of a variety of shapes.

Figure 12 illustrates another configuration of an exemplary Capacitive Micromachined Ultrasonic Transducer (CMUT) with non-coplanar actuation and displacement according to various embodiments. Referring to fig. 12, CMUT 1200 is similar to CMUT 600 or CMUT 900. CMUT 1200 comprises a plate 1202 with a central mass 1203 and a base 1204 with a recess 1205. The plate 1202 is coupled to the base 1204 such that substantially the entire top surface of the base 1204 is coupled to the corresponding bottom surface of the plate 1202. There may be a recess 1203A in the central mass 1203, where the specific dimensions of the recess 1203A may vary for various embodiments, and the shape of the recess 1203A may be any of various shapes.

Figure 13 illustrates another configuration of an exemplary Capacitive Micromachined Ultrasonic Transducer (CMUT) with non-coplanar actuation and displacement according to various embodiments. Referring to fig. 13, a top cross-sectional view (e.g., X-Y plane) of CMUT 1300 is shown, showing a pattern of horizontal gaps 1310. Also shown are side cross-sectional views (e.g., X-Z planes) 1302 and 1304, showing horizontal gaps 1312 between the electrodes and upper vertical gaps 1314. The horizontal gap 1312 may be similar to the horizontal gap 306 in fig. 3, and the upper vertical gap 1314 may be similar to the upper vertical gap 307 in fig. 3.

It can be seen that cross-sectional view 1302 is directed to an outer portion of horizontal gap 1310, and cross-sectional view 1304 is directed to an inner portion of horizontal gap 1310.

Figure 14 illustrates another configuration of an exemplary Capacitive Micromachined Ultrasonic Transducer (CMUT) with non-coplanar actuation and displacement according to various embodiments. Referring to fig. 14, a top cross-sectional view (e.g., X-Y plane) of CMUT 1400 is shown, showing a pattern of horizontal gaps 1410. Also shown are side cutaway views (e.g., X-Z planes) 1402 and 1404 showing horizontal gaps 1412 between electrodes and upper vertical gaps 1414. Horizontal gap 1412 may be similar to horizontal gap 306 in fig. 3, and upper vertical gap 1414 may be similar to upper vertical gap 307 in fig. 3.

It can be seen that cross-sectional view 1402 is directed to an outer portion of horizontal gap 1410, and cross-sectional view 1404 is directed to an inner portion of horizontal gap 1410.

While two exemplary configurations for increasing the total surface area of the electrodes for horizontal gap 1310 and horizontal gap 1410 of CMUTs 1300 and 1400, respectively, are shown, the horizontal gap may be any of a variety of shapes, such as circular, elliptical, regular polygonal, irregular polygonal, or the like, when viewed from the top (e.g., X-Y plane). The horizontal gap may be one or more discrete pieces that are continuous, do not completely surround the CMUT as shown in fig. 13 and 14, or surround the CMUT together. Thus, when viewed from above (e.g., the X-Y plane), the horizontal gaps of the CMUT may include one or more gaps, where each gap may be any geometric shape having any pattern.

Additionally, any CMUT may have any geometry when viewed from the top (e.g., X-Y plane). For example, although CMUT 1300 and CMUT 1400 are shown as circular, the CMUTs may be elliptical, oval, polygonal, and the like. Additionally, while several configurations are shown, the various embodiments of the present disclosure are not necessarily limited thereto. For example, CMUT 200 may have multiple electrodes 210 and 211 similar to CMUT 600. That is, while the edges may be planar, there may be multiple electrodes, which may be multiple electrodes 210 and corresponding multiple electrodes 211. Or there may be a different number of electrodes 210 than electrodes 211, where, for example, multiple electrodes 210 may be used for a single electrode 211, or vice versa.

Further, the central masses 203, 503, 603, 703, 803, 903, etc. may have different shapes than the disclosed examples. For example, the central mass 503 may have rounded (convex) edges and the recess 505 of the base 504 may have rounded (convex) edges, such that the recess 505 may receive the central mass 503. Accordingly, various embodiments of the present disclosure may have suitably rounded electrodes 506 and 507.

However, the shape of the central mass and/or the recess of the base need not be limited to those mentioned in this disclosure. Rather, any suitable shape may be used. Furthermore, the electrodes placed on the edge surfaces of the central block and/or the recess may have a shape that conforms to the edge surfaces or a shape that is different from the edge surfaces.

Additionally, although various descriptions of edges, surfaces, electrodes are described, the edges, surfaces, or electrodes may be a single continuous edge/surface/electrode. For example, when the central mass 203 is cylindrical, the central mass 203 may include a single vertical surface. Thus, CMUT 200 can have a single electrode 210 and a single electrode 211. However, even when there is a single surface, there may be a plurality of electrodes 210 and a plurality of electrodes 211 placed at regular intervals along a single surface of the central mass 203 of the plate 202 and/or a single surface of the recess 205 of the base 204.

Further, the gaps described in the various figures may be filled with a fluid, such as air, or may include a level of vacuum. Thus, in various embodiments of the present disclosure, the capacitive transducer may be configured such that the gap is airtight.

While various embodiments are disclosed with respect to capacitive micromachined ultrasonic transducers, the present disclosure is applicable to other types of transducers besides ultrasonic transducers. For example, a MEMS device using isolation layers may be able to use the disclosed embodiments to address charging issues in one or more isolation layers. Additionally, although the transducer is described in the field as being used for medical imaging, various other types of imaging may use the transducer. For example, in addition to ultrasound imaging of a person, an animal, or the like, the imaging apparatus may be used for ultrasound/acoustic sensing, non-destructive evaluation (NDE), ultrasound therapy (high intensity focused ultrasound (HIFU)), or the like.

Thus, as can be seen, the present disclosure provides a capacitive transducer comprising: a plate comprising a protruding central mass; a base having a central recess configured to receive the central mass; a first electrode coupled to a non-horizontal edge surface of the central mass; and a second electrode coupled to the non-horizontal edge surface of the central depression. The plate may be coupled to the substrate at least along an outer peripheral region of the plate and the substrate.

The non-horizontal edge surfaces of the central mass and the central recess may be substantially vertical surfaces. The non-horizontal edge surfaces of the central mass and the central recess may be angled surfaces. The non-horizontal edge surfaces of the central mass and the central recess may be rounded surfaces. The non-horizontal edge surfaces of the central mass and the central recess may be corrugated surfaces.

At least a portion of the top surface of the central mass may be non-coplanar with a portion of the top surface of the plate that is not the central mass. Substantially the entire top surface of the substrate may be coupled to the corresponding bottom surface of the plate.

There may be a first vertical gap between a bottom surface of the central mass and a bottom surface of the central recess, and a second vertical gap between a non-central mass portion of the plate and a top surface of the base. There may be a horizontal gap between the first electrode and the second electrode. The first vertical gap may be equal to the second vertical gap. The horizontal gap may be equal to one or both of the first vertical gap and the second vertical gap.

The first vertical gap, the second vertical gap, and the horizontal gap may be filled with a gas, such as air. The plate and the substrate may be configured to couple to form an airtight barrier around the gap. The first vertical gap, the second vertical gap, and the horizontal gap may include a substantially gas-free vacuum.

Various embodiments of the present disclosure may also provide a capacitive transducer including: a capacitive transducer comprising a plate having a protruding central mass, a base having a central recess configured to receive the central mass, a first electrode coupled to a non-horizontal edge surface of the central mass; and a second electrode coupled to the non-horizontal edge surface of the central recess.

The plate may be coupled to the base at least along outer peripheral regions of the plate and the base, and the non-horizontal edge surface of the central mass and the non-horizontal edge surface of the central recess may be substantially vertical surfaces.

There may be a first vertical gap between a bottom surface of the central mass and a bottom surface of the central recess, and a second vertical gap between a non-central mass portion of the plate and a top surface of the base. There may be a horizontal gap between the first electrode and the second electrode. At least a portion of the top surface of the central mass is non-coplanar with a portion of the top surface of the plate that is not the central mass.

Substantially the entire top surface of the base is coupled to the corresponding bottom surface of the plate, and the horizontal gap may be equal to one or both of the first vertical gap and the second vertical gap.

Various embodiments of the present disclosure may also provide a capacitive transducer including: a plate comprising a protruding central mass; a base having a central recess configured to receive the central mass; a first electrode coupled to a non-horizontal edge surface of the central mass; and a second electrode coupled to the non-horizontal edge surface of the central depression.

The plate may be coupled to the base at least along outer peripheral regions of the plate and the base, the non-horizontal edge surface of the central mass and the non-horizontal edge surface of the central recess may be substantially vertical surfaces, and at least a portion of the top surface of the central mass is non-coplanar with a portion of the top surface of the plate that is not the central mass. Substantially the entire top surface of the substrate may be coupled to the corresponding bottom surface of the plate.

As used herein, the term "circuitry" refers to physical electronic components (i.e., hardware) as well as configurable hardware, any software and/or firmware ("code") executed by and/or otherwise associated with hardware. For example, as used herein, a particular processor and memory may comprise first "circuitry" when executing one or more first codes and may comprise second "circuitry" when executing one or more second codes. As used herein, "and/or" means any one or more of the items in the list joined by "and/or". For example, "x and/or y" represents any element of the three-element set { (x), (y), (x, y) }. As another example, "x, y, and/or z" represents any element of the seven-element set { (x), (y), (z), (x, y), (x, z), (y, z), (x, y, z) }. The term "exemplary", as used herein, means serving as a non-limiting example, instance, or illustration. As used herein, the terms "e.g., (e.g.)" and "e.g., (for example)" bring forth a list of one or more non-limiting examples, instances, or illustrations. As used herein, a circuit is "operable to" and/or "configured to" perform a function whenever the circuit includes the necessary hardware and code (if needed) to perform the function, regardless of whether execution of the function is disabled or not enabled by certain user-configurable settings.

While the disclosure has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the scope thereof. Therefore, it is intended that the disclosure not be limited to the particular embodiments disclosed, but that the disclosure will include all embodiments falling within the scope of the appended claims.