Abstract: In some implementations, a capacitive micromachined ultrasonic transducer (CMUT) apparatus includes one or more CMUTs or CMUT arrays, an acoustic window, a coupling medium, and a packaging substrate. The acoustic window may have various configurations, such as for reducing acoustic reflectance or increasing mechanical properties. In some examples, at least one of the CMUTs, the acoustic window or the coupling medium may include a focusing capability for focusing acoustic energy to or from the CMUT.

Abstract: A through-wafer interconnect and a method for fabricating the same are disclosed. The method starts with a conductive wafer to form a patterned trench by removing material of the conductive wafer. The patterned trench extends in depth from the front side to the backside of the wafer, and has an annular opening generally dividing the conductive wafer into an inner portion and an outer portion whereby the inner portion of the conductive wafer is insulated from the outer portion and serves as a through-wafer conductor. A dielectric material is formed or added into the patterned trench mechanical to support and electrically insulate the through-wafer conductor. Multiple conductors can be formed in an array.

Abstract: A method as disclosed makes a capacitive micromachined ultrasonic transducer (cMUT). The method forms a pattern of standing features on a substrate to serve as support walls in the cMUT being made, and further makes a patterned trench from the front side into the substrate at selected locations where separation boundaries of neighboring elements of the cMUT are located. In the process of completing the transducer elements of the cMUT, the method forms a covering layer over the patterned trench to at least temporarily cover the patterned trench. The covering layer seals the patterned trench to prevent other materials from entering during at least a part of the fabrication process.

Abstract: An electrostatic actuator/transducer has a comb driver and can be adapted for a variety of applications, particularly as a capacitive micromachined ultrasonic transducer. The comb driver has two electrodes each connected to a set of comb fingers. The two sets of comb fingers interdigitate with each other, and in one embodiment each has a saw-toothed shape. One electrode is connected to a spring structure and movable along a vertical direction to engage and disengage the two sets of comb fingers. The movable portion is adapted to perform an actuation function and/or a sense of function. Fabrication methods for making the electrostatic actuator/transducer are also disclosed.

Abstract: A capacitive micromachined ultrasound transducer (cMUT) is provided. The cMUT has a first layer having a first electrode and a second layer having a second electrode opposing the first electrode to define a gap width therebetween. At least one of the first layer and the second layer includes a flexible layer having a contact area in contact to a support, such that the first electrode and the second electrode are movable relative to each other to cause a change of the gap width. The support has two substantially continuous shoulder sides each extending along with the flexible layer, each shoulder side making graduated contact with more contact area of the flexible layer as the flexible layer deforms toward the shoulder side, causing the flexible layer to have a dynamically changing spring strength.

Abstract: A capacitive micromachined ultrasound transducer (cMUT) and fabrication method of the same are provided. The cMUT has a substrate, a curved membrane disposed on top of the substrate, and a flexible membrane disposed on top of the curved membrane. The curved membrane has a raised portion which is higher than a recessed portion relative to the substrate, and is supported by a support standing on a major surface of the substrate. The flexible membrane includes a first region mounted to the raised portion of the curved membrane, and a second region extending over the recessed portion of the curved member. Methods for fabricating the cMUT are also disclosed.

Abstract: A method for a capacitive micromachined ultrasound transducer (cMUT) is provided. The method grows and patterns a diffusion barrier layer over a surface of a base layer. The diffusion barrier layer have different areas that allow different levels of diffusion penetration. A diffusion process is performed over the diffusion barrier layer such that a diffusion reactivated material reaches different depths into the base layer below the different areas. A anchor is formed using the diffusion reactivated material. The anchor has a lower portion below a major surface of the base layer and an upper portion above the major surface of the base layer. A cover layer is placed over the anchor and the base layer. At least one of the cover layer and the base layer includes a flexible layer, such that the cMUT electrodes are movable relative to each other to cause a change of the gap width.

Abstract: A micro-electro-mechanical transducer (such as a cMUT) having a non-flat surface is disclosed. The non-flat surface may include a variable curve or slope in an area where a spring layer contacts a support, thus making a variable spring model as the spring layer vibrates. The non-flat surface may be that of a non-flat electrode optimized to compensate the dynamic deformation of the other electrode during operation and thus enhance the uniformity of the dynamic electrode gap during operation. Methods for fabricating the micro-electro-mechanical transducer are also disclosed. The methods may be used in both conventional membrane-based cMUTs and cMUTs having embedded springs transporting a rigid top plate.

Abstract: Some examples include at least one capacitive micro-electro-mechanical transducer (cMUT). For instance, the cMUT may include a substrate, a plate, and a resilient structure therebetween. In some examples, an integrated circuit may be formed on or integrated with the plate or other portion of the cMUT. Furthermore, in some examples, two cMUTs may be arranged in a stacked configuration. For instance, one cMUT may be operable for transmission, while a second cMUT may be operable for reception.

Abstract: A curved or bendable micro-electro-mechanical transducer (such as the cMUT) is disclosed. The transducer has a plurality of transducer elements built on a substrate. The substrate has a slot below every two neighboring device elements. Each slot is at least at least partially filled with a flexible material to allow bending of the substrate. A bending actuator may be included to facilitate the bending of the substrate. An exemplary bending actuator uses a nonuniformly shrinkable material to bend the substrate. A curved or bendable cMUT of the present invention can be configured to be an intravascular ultrasound (IVUS) device.

Abstract: Embodiments of a method for packaging cMUT arrays allow packaging multiple cMUT arrays on the same packaging substrate introduced over a side of the cMUT arrays. The packaging substrate is a dielectric layer on which openings are patterned for depositing a conductive layer to connect a cMUT array to VO pads interfacing with external devices. Auxiliary system components may be packaged together with the cMUT arrays. Multiple cMUT arrays and optionally multiple auxiliary system components can be held in place by a larger support structure for batch production. The support structure can be made of an arbitrary size using inexpensive materials.

Abstract: A micro-electro-mechanical transducer (such as a cMUT) having two electrodes separated by an insulator with an insulation extension is disclosed. The two electrodes define a transducing gap therebetween. The insulator has an insulating support disposed generally between the two electrodes and an insulation extension extending into at least one of two electrodes to increase the effective insulation without having to increase the transducing gap. Methods for fabricating the micro-electro-mechanical transducer are also disclosed. The methods may be used in both conventional membrane-based cMUTs and cMUTs having embedded springs transporting a rigid top plate.

Abstract: Implementations of a cMUT have a telemetric antenna operative to telemetrically transmit an output signal generated by the cMUT in reception mode (RX). The cMUT generates the output signal by converting a received energy applied on the cMUT. The received energy may be an acoustic wave or a low-frequency pressure signal. The acoustic wave may be generated by a separate acoustic energy source. The cMUT may form a modulated signal using a carrier signal modulated with the output signal, and telemetrically transmit the modulated signal carrying the output signal to increase efficiency. The antenna may also receive an input signal from outside to telemetrically power on the cMUT.

Abstract: In some implementations, a capacitive micromachined ultrasonic transducer (CMUT) apparatus includes one or more CMUTs or CMUT arrays, an acoustic window, a coupling medium, and a packaging substrate. The acoustic window may have various configurations, such as for reducing acoustic reflectance or increasing mechanical properties. In some examples, at least one of the CMUTs, the acoustic window or the coupling medium may include a focusing capability for focusing acoustic energy to or from the CMUT.

Abstract: Implementations of a cMUT have dual operation modes. The cMUT has two different switchable operating conditions depending on whether a spring member in the cMUT contacts an opposing surface at a contact point in the cMUT. The two different operating conditions have different frequency responses due to the contact. The cMUT can be configured to operate in transmission mode when the cMUT in the first operating condition and to operate in reception mode when the cMUT is in the second operating condition. The implementations of the dual operation mode cMUT are particularly suitable for ultrasonic harmonic imaging in which the reception mode receives higher harmonic frequencies.

Abstract: Implementations of a capacitive micromachined ultra-sonic transducer (CMUT) include a feedback component connected in series with the CMUT. The feedback component applies a feedback on a voltage applied on the CMUT for affecting the voltage applied on the CMUT as a capacitance of the CMUT changes during actuation of the CMUT.

Abstract: A capacitive micromachined ultrasonic transducer (CMUT) includes a structured membrane which possesses improved frequency response characteristics. Some embodiments provide CMUTs which include a substrate, a first electrode, a second movable electrode, and a structured membrane. The movable second electrode is spaced apart from the first electrode and is coupled to the structured membrane. The structured membrane is shaped to possess a selected resonant frequency or an optimized frequency response. The structured membrane can include a plate and a beam coupled to the plate such that the resonant frequency of the structured membrane is greater than the resonant frequency of the plate. Furthermore, the ratio of the resonant frequency of the structured membrane over the mass of the structured membrane can be greater than the ratio of the resonant frequency of the plate over the mass of the plate. In some embodiments, the CMUT is an embedded spring ESCMUT.

Abstract: A method for fabricating electrostatic transducers and arrays electrically separates the substrate segments of the transducer elements from each other using a technique involving two cutting steps, in which the first step forms a patterned opening in the substrate to make a partial separation of substrate segments, and the second step completes the separation after the substrate segments have been secured to prevent instability of the substrate segments upon completion of the second step. The securing of the substrate segments may be accomplished by filling a nonconductive material in the partial separation or securing the transducer array on a support substrate. When the substrate is conductive, the separated substrate segments serve as separate bottom electrodes that can be individually addressed. The method is especially useful for fabricating ID transducer arrays.

Abstract: A cMUT and a cMUT operation method use an input signal that has two components with different frequency characteristics. The first component has primarily acoustic frequencies within a frequency response band of the cMUT, while the second component has primarily frequencies out of the frequency response band. The bias signal and the second component of the input signal together apply an operation voltage on the cMUT. The operation voltage is variable between operation modes, such as transmission and reception modes. The cMUT allows variable operation voltage by requiring only one AC component. This allows the bias signal to be commonly shared by multiple cMUT elements, and simplifies fabrication. The implementations of the cMUT and the operation method are particularly suitable for ultrasonic harmonic imaging in which the reception mode receives higher harmonic frequencies.

Abstract: Implementations include a capacitive micromachined ultrasonic transducer (CMUT) having an additional transducing device overlaid in a vertically stacked relationship. In some implementations the additional transducing device is a second CMUT configured to operate at a different frequency from the first CMUT.