Capacitive Micromachined Ultrasonic Transducers

Abstract

Systems, devices, and methods related to a capacitive micromachined ultrasonic transducer (CMUT) are provided. The CMUT includes an electrode and a plate overlying the electrode forming a cavity. The electrode is a contoured electrode and / or the plate is a contoured plate. A voltage applied across the electrode and the plate deflects the plate. The cavity is a non-uniform cavity space between the plate and the electrode, the cavity space being largest in a central region of the plate.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 286,161 (Docket No. USD-008-PR1), entitled “Capacitive Micromachined Ultrasonic Transducer,” filed December 6, 2021, the contents of which are incorporated by reference in their entirety herein for all purposes.

[0002] This application is related to U.S. Provisional Patent Application No. 62 / 728,616, filed September 7, 2018, and entitled “Medical Device with CMUT Array and Solid State Cooling, and Associated Methods and Systems-with Thermal Analysis” (Docket No. USD-001-PR), the contents of which are incorporated by reference in their entirety for all purposes.

[0003] This application is related to U.S. Application No. 16 / 130,896 (docket no. USD-001-US), filed September 13, 2018, entitled “Medical Device with CMUT Array and Solid State Cooling, and Associated Methods and Systems,” and U.S. Patent No. 11,154,730, issued October 26, 2021, the contents of which are incorporated by reference in their entirety for all purposes.

[0004] This application is related to U.S. Patent Application No. 17 / 479,011 (Docket No. USD-001-US-CON1), filed September 20, 2021, entitled "Medical Device with CMUT Array and Solid State Cooling, And Associated Methods and Systems," and U.S. Publication No. US2022 / 0072338, published March 10, 2022, the contents of which are incorporated by reference in their entirety into this specification for all purposes.

[0005] This application is related to International PCT Patent Application No. PCT / US2018 / 050943 (Docket No. USD-001-PCT), filed September 13, 2018, entitled “Medical Device with CMUT Array and Solid State Cooling, and Associated Methods and Systems,” and Publication No. WO2019 / 055699, published March 21, 2019, the contents of which are incorporated by reference in their entirety for all purposes.

[0006] This application is related to U.S. Provisional Patent Application No. 63 / 126,078 (Docket No. USD-003-PR1), entitled "Tissue Interface System," filed on December 16, 2020, the contents of which are incorporated by reference in their entirety into this specification for all purposes.

[0007] This application is related to International PCT Patent Application No. PCT / US2021 / 063743 (Docket No. USD-003-PCT), filed December 16, 2021, entitled "Tissue Interface System," and Publication No. WO2022 / 133054, published June 23, 2022, the contents of which are incorporated by reference in their entirety herein for all purposes.

[0008] This application is related to U.S. Provisional Patent Application No. 63 / 195,292 (Docket No. USD-004-PR1), entitled "Tissue Interface System," filed June 1, 2021, the contents of which are incorporated by reference in their entirety into this specification for all purposes.

[0009] This application is International PCT Patent Application No. PCT / US22 / 031746 (Docket No. USD-004-PCT), filed June 1, 2022, entitled "Tissue Treatment System," and is related to International Publication No. WO 2022 / 256388, published August 12, 2022, the contents of which are incorporated by reference in their entirety herein for all purposes.

[0010] Field of inventive concepts The inventive concepts relate generally to ultrasonic transducers, such as capacitive micromachined ultrasonic transducers (CMUT). [Background technology]

[0011] Capacitive Micromachined Ultrasound Transducers (CMUTs) are an alternative to piezoelectric ultrasound transducers. CMUTs may be used in a variety of applications, including medical imaging, other imaging, therapeutic, high intensity focused ultrasound (HIFU), and chemical detection applications. CMUTs may be used to transmit and / or receive ultrasound. CMUTs used to transmit ultrasound energy have a transmit output pressure. CMUTs used in receiving applications have a receive sensitivity. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] US Patent Application Publication No. 2021 / 0220873 [Patent Document 2] US Patent Application Publication No. 2019 / 0336104 [Patent Document 3] U.S. Patent No. 8,952,595 [Patent Document 4] US Patent Application Publication No. 2021 / 0060610 [Patent Document 5] International Publication No. 2021 / 007555 Summary of the Invention [Problem to be solved by the invention]

[0013] Improving the transmit power output and / or receive sensitivity of CMUTs is desirable. Embodiments of the systems, devices, and methods described herein may be directed to systems, devices, and methods for capacitive micromachined ultrasonic transducers (CMUTs). [Means for solving the problem]

[0014] In accordance with one aspect of the inventive concept, a capacitive micromachined ultrasonic transducer (CMUT) includes an electrode and a plate overlying the electrode to form a cavity. The electrode may include a contoured electrode and / or the plate may include a contoured plate. A voltage applied across the electrode and the plate may deflect the plate. The cavity may include a non-uniform cavity space between the plate and the electrode, with the cavity space being largest in a central region of the plate.

[0015] In some embodiments, the electrode comprises a contoured electrode and the plate comprises a contoured plate.

[0016] In some embodiments, either the electrodes comprise contoured electrodes or the plates comprise contoured plates.

[0017] In some embodiments, the CMUT further includes a sensing electrode.

[0018] In some embodiments, the plate includes a contoured plate. The two-dimensional cross-sectional profile of the contoured plate may be one or more of piecewise linear, curved, and stepped. The contoured plate may include one or more of at least one planar portion, at least one concave portion, and at least one convex portion. The CMUT may be configured to operate in a collapse mode.

[0019] In some embodiments, the CMUT comprises a piston-based CMUT and the plate further comprises a piston. The plate may comprise a contoured electrode. A two-dimensional cross-sectional profile of the contoured electrode may be one or more of piece-wise linear, curved, and stepped. The plate may comprise a contoured plate. A two-dimensional cross-sectional profile of the contoured plate may be one or more of piece-wise linear, curved, and stepped. The CMUT may be configured to operate in a collapse mode.

[0020] In some embodiments, the CMUT includes an air-compatible CMUT further comprising an air vent. The electrode may include a contoured electrode. A two-dimensional cross-sectional profile of the contoured electrode may be one or more of piece-wise linear, curved, and stepped. The plate may include a contoured plate. A two-dimensional cross-sectional profile of the contoured plate may be one or more of piece-wise linear, curved, and stepped. The CMUT may further include a fluidic trench. The air-compatible CMUT may include a piston-based CMUT, where the plate may further include a piston. The air-compatible CMUT may include a piston-based CMUT, where the plate may further include a piston.

[0021] In some embodiments, the CMUT further includes an insulating film disposed between the plate and the electrode, such as an insulating film disposed on the plate, an insulating film disposed on the electrode, or a first insulating film disposed on the plate and a second insulating film disposed on the electrode. The insulating film may include a contoured insulating film. The insulating film may include two or more materials. The two or more materials may include different dielectric constants.

[0022] In some embodiments, the CMUT is configured to operate in a collapse mode. The CMUT can be configured to operate in multiple collapse modes.

[0023] In some embodiments, the CMUT array includes a plurality of CMUTs.

[0024] In some embodiments, the CMUT further includes a plate support that surrounds the electrode and is in contact with the plate.

[0025] According to another aspect of the inventive concept, a system includes one or more CMUTs and a device integrated with one or more CMUTs. The device may include a medical device. The medical device may include a device selected from a group consisting of devices that deliver ultrasonic energy to tissue to, for example, stimulate, ablate, and / or image tissue, drug delivery devices, cardiac pacing devices, neuroablation devices, and combinations thereof. The medical device may be configured to deliver ultrasonic energy through one or more CMUTs to both image and ablate tissue. The device may include a processor including a memory storage module, which may store instructions for the controller to execute an algorithm. The algorithm may include an artificial intelligence algorithm. The algorithm may be configured to modify a drive signal provided to one or more CMUTs. The device may include a functional element including one or more sensors, which may be configured to record physiological information of a patient receiving ultrasonic energy from one or more CMUTs, and the algorithm may be configured to adjust a drive signal provided to one or more CMUTs based on the recorded physiological information.

[0026] According to another aspect of the inventive concept, a method for manufacturing a CMUT includes an oxidation process, an etching process, and / or a doping process, for example, where one or more of the processes used result in contoured (e.g., non-linearly shaped) components.

[0027] The technology described herein, together with its attributes and attendant advantages, will best be appreciated and understood by considering the following detailed description in conjunction with the accompanying drawings in which representative embodiments are illustrated by way of example.

[0028] Incorporation by Reference All publications, patents, and patent applications mentioned within this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference. The contents of all publications, patents, and patent applications mentioned herein are incorporated by reference in their entireties for all purposes. [Brief description of the drawings]

[0029] [Figure 1] 1 shows a schematic diagram of a system including a device with at least one capacitive micromachined ultrasonic transducer (CMUT) consistent with the concepts of the present invention. [Figure 1A] 1A-1C show cross-sectional views of two examples of current (e.g., commercially available) CMUT structures consistent with the concepts of the present invention. [Figure 1B] 1A-1C show cross-sectional views of two examples of current (e.g., commercially available) CMUT structures consistent with the concepts of the present invention. [Diagram 2] 1 shows a top view of a plate of a CMUT including a sensing electrode consistent with the concepts of the present invention. [Diagram 3] 1 illustrates an array of transducers including CMUT components and sensing transducers consistent with the concepts of the present invention. [Figure 4A] 1A-1D show various cross-sectional views of a CMUT component configuration including a shaped plate consistent with the concepts of the present invention. [Figure 4B] 1A-1D show various cross-sectional views of a CMUT component configuration including a shaped plate consistent with the concepts of the present invention. [Figure 4C] 1A-1D show various cross-sectional views of a CMUT component configuration including a shaped plate consistent with the concepts of the present invention. [Figure 4D]1A-1D show various cross-sectional views of a CMUT component configuration including a shaped plate consistent with the concepts of the present invention. [Figure 4E] 1A-1D show various cross-sectional views of a CMUT component configuration including a shaped plate consistent with the concepts of the present invention. [Figure 5A] 1A-1D show various cross-sectional views of a CMUT component configuration including a shaped plate consistent with the concepts of the present invention. [Figure 5B] 1A-1D show various cross-sectional views of a CMUT component configuration including a shaped plate consistent with the concepts of the present invention. [Figure 5C] 1A-1D show various cross-sectional views of a CMUT component configuration including a shaped plate consistent with the concepts of the present invention. [Figure 5D] 1A-1D show various cross-sectional views of a CMUT component configuration including a shaped plate consistent with the concepts of the present invention. [Figure 6A] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 6B] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 6C] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 6D] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 6E] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 6F] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 6G] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 6H] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 6I] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 7A] 1A-1D show various cross-sectional views of piston-based CMUT components including shaped plates and / or shaped bottom electrodes consistent with the concepts of the present invention. [Figure 7B] 1A-1D show various cross-sectional views of piston-based CMUT components including shaped plates and / or shaped bottom electrodes consistent with the concepts of the present invention. [Figure 7C] 1A-1D show various cross-sectional views of piston-based CMUT components including shaped plates and / or shaped bottom electrodes consistent with the concepts of the present invention. [Figure 7D] 1A-1D show various cross-sectional views of piston-based CMUT components including shaped plates and / or shaped bottom electrodes consistent with the concepts of the present invention. [Figure 7E] 1A-1D show various cross-sectional views of piston-based CMUT components including shaped plates and / or shaped bottom electrodes consistent with the concepts of the present invention. [Figure 8A] 1A-1D show various cross-sectional views of piston-based CMUT components including shaped plates and / or shaped bottom electrodes consistent with the concepts of the present invention. [Figure 8B] 1A-1D show various cross-sectional views of piston-based CMUT components including shaped plates and / or shaped bottom electrodes consistent with the concepts of the present invention. [Figure 8C] 1A-1D show various cross-sectional views of piston-based CMUT components including shaped plates and / or shaped bottom electrodes consistent with the concepts of the present invention. [Figure 8D] 1A-1D show various cross-sectional views of piston-based CMUT components including shaped plates and / or shaped bottom electrodes consistent with the concepts of the present invention. [Figure 9A] 1A-1D show various cross-sectional views of piston-based CMUT components including shaped plates and / or shaped bottom electrodes consistent with the concepts of the present invention. [Figure 9B] 1A-1D show various cross-sectional views of piston-based CMUT components including shaped plates and / or shaped bottom electrodes consistent with the concepts of the present invention. [Figure 9C] 1A-1D show various cross-sectional views of piston-based CMUT components including shaped plates and / or shaped bottom electrodes consistent with the concepts of the present invention. [Figure 9D] 1A-1D show various cross-sectional views of piston-based CMUT components including shaped plates and / or shaped bottom electrodes consistent with the concepts of the present invention. [Figure 9E] 1A-1D show various cross-sectional views of piston-based CMUT components including shaped plates and / or shaped bottom electrodes consistent with the concepts of the present invention. [Figure 10A] 1A-1D show various cross-sectional views of piston-based CMUT components including shaped plates and / or shaped bottom electrodes consistent with the concepts of the present invention. [Figure 10B] 1A-1D show various cross-sectional views of piston-based CMUT components including shaped plates and / or shaped bottom electrodes consistent with the concepts of the present invention. [Figure 10C] 1A-1D show various cross-sectional views of piston-based CMUT components including shaped plates and / or shaped bottom electrodes consistent with the concepts of the present invention. [Figure 10D] 1A-1D show various cross-sectional views of piston-based CMUT components including shaped plates and / or shaped bottom electrodes consistent with the concepts of the present invention. [Figure 11A] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 11B] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 11C] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 11D] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 12] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 13] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 14A] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 14B]1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 15A] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 15B] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 16A] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 16B] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 17A] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 17B] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 18A] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 18B] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 18C] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 19] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 20] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 21A] 1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 21B] 1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 21C] 1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 21D] 1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 21E] 1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 22A] 1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 22B] 1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 22C] 1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 22D] 1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 23A] 1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 23B] 1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 23C] 1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 23D] 1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 23E]1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 24A] 1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 24B] 1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 24C] 1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 24D] 1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 25A] 1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 25B] 1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 25C] 1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 25D] 1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 25E] 1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 26A] 1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 26B]1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 26C] 1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 26D] 1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 27A] 1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 27B] 1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 27C] 1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 27D] 1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 27E] 1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 28A] 1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 28B] 1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 28C] 1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 28D]1A-1C show various cross-sectional views of a CMUT component configured for airborne applications and including a shaped plate and / or a shaped bottom electrode consistent with the concepts of the present invention. [Figure 29A] 1A-1D show top views of a portion of a CMUT component including various patterns of fluidic trenches consistent with the concepts of the present invention. [Figure 29B] 1A-1D show top views of a portion of a CMUT component including various patterns of fluidic trenches consistent with the concepts of the present invention. [Figure 29C] 1A-1D show top views of a portion of a CMUT component including various patterns of fluidic trenches consistent with the concepts of the present invention. [Figure 29D] 1A-1D show top views of a portion of a CMUT component including various patterns of fluidic trenches consistent with the concepts of the present invention. [Figure 30A] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 30B] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 30C] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 30D] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 30E] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 30F] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 30G] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 30H] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 30I] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 30J] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 30K] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 30L] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 30M] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 30N] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 30O] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 30P] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 30Q] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 30R] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 30S] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 30T] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Fig. 30U] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 30V] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Fig. 30W] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Fig. 30X]1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Figure 30Y] 1 shows various charts and graphs of CMUT output power and other performance characteristics consistent with the inventive concepts. [Diagram 31] 1 shows a cross-sectional view of an embodiment of a CMUT with a shaped dielectric consistent with the concepts of the present invention. [Figure 31A] FIG. 2 is a schematic diagram illustrating the capacitance of a CMUT consistent with the concepts of the present invention. [Figure 31B] 1A-1D show cross-sectional views of various CMUT components including shaped dielectric films consistent with the concepts of the present invention. [Figure 31C] 1A-1D show cross-sectional views of various CMUT components including shaped dielectric films consistent with the concepts of the present invention. [Diagram 32] 1 shows a cross-sectional view of a CMUT including a multi-layer dielectric consistent with the concepts of the present invention. [Diagram 33] 1 illustrates a sequence of steps for manufacturing a CMUT with a stepped profile dielectric film consistent with the concepts of the present invention. [Diagram 34] 1 illustrates a sequence of steps for manufacturing a CMUT with a stepped profile bottom electrode and a stepped profile dielectric film consistent with the concepts of the present invention. [Figure 35A] 1 shows a cross-sectional view of an analyzed CMUT configuration, consistent with the inventive concepts, and graphs of transmit and receive sensitivity for the illustrated CMUT configuration. [Figure 35B] 1 shows a cross-sectional view of an analyzed CMUT configuration, consistent with the inventive concepts, and graphs of transmit and receive sensitivity for the illustrated CMUT configuration. [Figure 35C] 1 shows a cross-sectional view of an analyzed CMUT configuration, consistent with the inventive concepts, and graphs of transmit and receive sensitivity for the illustrated CMUT configuration. [Figure 35D] 1 shows a cross-sectional view of an analyzed CMUT configuration, consistent with the inventive concepts, and graphs of transmit and receive sensitivity for the illustrated CMUT configuration. [Diagram 36] 1 illustrates a sequence of steps for a method of fabricating a CMUT including a shaped bottom electrode consistent with the concepts of the present invention. [Figure 37]1 illustrates a sequence of steps for a method of forming a graded silicon layer consistent with the concepts of the present invention. [Figure 38] 1 illustrates a sequence of steps for a method of forming a shaped silicon layer consistent with the concepts of the present invention. [Figure 39] 1 illustrates a sequence of steps for a method of manufacturing a CMUT with a shaped plate consistent with the concepts of the present invention. [Diagram 40] 1 illustrates a sequence of steps for a method of fabricating a CMUT with a shaped bottom electrode consistent with the concepts of the present invention. [Diagram 41] 1 illustrates a sequence of steps for a method of fabricating a CMUT with a shaped bottom electrode consistent with the concepts of the present invention. [Diagram 42] 1 illustrates a sequence of steps for a method of manufacturing a CMUT with a shaped plate consistent with the concepts of the present invention. [Diagram 43] 1 illustrates a sequence of steps for a method of fabricating a top plate for a CMUT consistent with the concepts of the present invention. [Diagram 44] 1 illustrates a sequence of steps for a method of fabricating a top plate for a CMUT consistent with the concepts of the present invention. [Figure 45A] 1 shows cross-sectional schematic diagrams of various CMUT designs and graphs of CMUT performance consistent with the concepts of the present invention. [Figure 45B] 1 shows cross-sectional schematic diagrams of various CMUT designs and graphs of CMUT performance consistent with the concepts of the present invention. [Figure 45C] 1 shows cross-sectional schematic diagrams of various CMUT designs and graphs of CMUT performance consistent with the concepts of the present invention. [Figure 45D] 1 shows cross-sectional schematic diagrams of various CMUT designs and graphs of CMUT performance consistent with the concepts of the present invention. [Figure 46A] 1A-1C show various examples of component geometries before and after an oxidation process used in the fabrication of CMUTs consistent with the concepts of the present invention. [Figure 46B] 1A-1C show various examples of component geometries before and after an oxidation process used in the fabrication of CMUTs consistent with the concepts of the present invention. [Figure 46C]1A-1C show various examples of component geometries before and after an oxidation process used in the fabrication of CMUTs consistent with the concepts of the present invention. [Figure 46D] 1A-1C show various examples of component geometries before and after an oxidation process used in the fabrication of CMUTs consistent with the concepts of the present invention. [Figure 46E] 1A-1C show various examples of component geometries before and after an oxidation process used in the fabrication of CMUTs consistent with the concepts of the present invention. [Figure 46F] 1A-1C show various examples of component geometries before and after an oxidation process used in the fabrication of CMUTs consistent with the concepts of the present invention. [Figure 46G] 1A-1C show various examples of component geometries before and after an oxidation process used in the fabrication of CMUTs consistent with the concepts of the present invention. [Fig. 46H] 1A-1C show various examples of component geometries before and after an oxidation process used in the fabrication of CMUTs consistent with the concepts of the present invention. [Figure 46I] 1A-1C show various examples of component geometries before and after an oxidation process used in the fabrication of CMUTs consistent with the concepts of the present invention. [Figure 46J] 1A-1C show various examples of component geometries before and after an oxidation process used in the fabrication of CMUTs consistent with the concepts of the present invention. [Figure 46K] 1A-1C show various examples of component geometries before and after an oxidation process used in the fabrication of CMUTs consistent with the concepts of the present invention. [Figure 46L] 1A-1C show various examples of component geometries before and after an oxidation process used in the fabrication of CMUTs consistent with the concepts of the present invention. [Figure 46M] 1A-1C show various examples of component geometries before and after an oxidation process used in the fabrication of CMUTs consistent with the concepts of the present invention. [Figure 46N] 1A-1C show various examples of component geometries before and after an oxidation process used in the fabrication of CMUTs consistent with the concepts of the present invention. [Figure 47A] 1A and 1B show top and side views, respectively, of a CMUT plate including a solid piston consistent with the concepts of the present invention. [Figure 47B]1A and 1B show top and side views, respectively, of a CMUT plate including a solid piston consistent with the concepts of the present invention. [Figure 48A] 1A and 1B show top and side views, respectively, of a CMUT plate including a non-solid piston consistent with the concepts of the present invention. [Figure 48B] 1A and 1B show top and side views, respectively, of a CMUT plate including a non-solid piston consistent with the concepts of the present invention. [Figure 49] 1 illustrates a sequence of steps for a method of fabricating a CMUT having a shaped profile consistent with the concepts of the present invention. [Figure 50] 1 illustrates another sequence of steps for a method of fabricating a CMUT having a shaped profile consistent with the concepts of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] Reference will now be made in detail to the present embodiments of the present technology, examples of which are illustrated in the accompanying drawings. Like reference numerals may be used to refer to like elements. However, this description is not intended to limit the disclosure to the particular embodiments, but should be construed as including various modifications, equivalents, and / or alternatives to the embodiments described herein.

[0031] As used herein, "comprising" (and any form of comprising, e.g., "comprise" and "comprises"), "having" (and any form of having, e.g., "have" and "has"), "including" (and any form of including, e.g., "includes" and "include"), or "containing" (and any form of containing, e.g., "contains" and "contain") specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0032] It will be further understood that, although terms such as first, second, third, etc. may be used herein to describe various limits, elements, components, regions, layers, and / or sections, these limits, elements, components, regions, layers, and / or sections should not be limited by these terms. These terms are used only to distinguish one limit, element, component, region, layer, or section from another limit, element, component, region, layer, or section. Thus, a first limit, element, component, region, layer, or section described below may be referred to as a second limit, element, component, region, layer, or section without departing from the teachings of the present application.

[0033] It will be further understood that when an element is referred to as being "on," "mounted," "connected," or "coupled" to another element, it may be directly on, above, or connected to or coupled to the other element, or there may be one or more intervening elements. In contrast, when an element is referred to as being "directly on," "directly mounted," "directly connected," or "directly coupled" to another element, there are no intervening elements present. Other words used to describe relationships between elements should be interpreted similarly (e.g., "between" and "directly between," "adjacent" and "directly adjacent," etc.).

[0034] As used herein, the terms "operably attached," "operably connected," and similar terms relating to attachment of components refer to attachment of two or more components that results in one, two, or more of an electrical attachment, a fluid attachment, a magnetic attachment, a mechanical attachment, an optical attachment, an acoustic attachment, and / or other operative attachment arrangement. The operative attachment of two or more components may facilitate the transfer of power, signals, electrical energy, fluid or other flowable materials, magnetism, mechanical coupling, light, sound such as ultrasound, and / or other materials and / or components between the two or more components.

[0035] It will be further understood that when a first element is referred to as being "in," "on," and / or "within" a second element, the first element may be disposed within an interior space of the second element, within a portion of the second element (e.g., within a wall of the second element), disposed on an exterior and / or interior surface of the second element, and combinations of one or more of these.

[0036] As used herein, the term "proximate," when used to describe the proximity of a first component or location to a second component or location, should be interpreted to include one or more locations near the second component or location, as well as in, on, and / or within the second component or location. For example, a component that is positioned proximate to an anatomical site (e.g., a target tissue location) is intended to include a component that is positioned near the anatomical site, as well as a component that is positioned in, on, and / or within the anatomical site.

[0037] Spatially relative terms, such as "below," "lower," "bottom," "upper," "top," etc., may be used to describe the relationship of an element and / or feature to another element(s) and / or feature(s), for example, as shown in the drawings. It will be further understood that the spatially relative terms are intended to encompass different orientations of the device in use and / or operation in addition to the orientation shown in the drawings. For example, if the device in the drawings were turned over, elements described as "below" and / or "below" other elements or features would then be oriented "above" the other elements or features. The device may be otherwise oriented (e.g., rotated 90 degrees, or to other orientations) and the spatially relative descriptors used herein would be interpreted accordingly.

[0038] As used herein, the terms "reduce," "reducing," "reduction," and the like are intended to include a reduction in amount, including a reduction to zero. Reducing the likelihood of occurrence is intended to include prevention of occurrence. Similarly, the terms "prevent," "preventing," and "prevention" are intended to include the acts of "reduce," "reducing," and "reducing," respectively.

[0039] The term "and / or" as used herein should be construed as a specific disclosure of each of the two specified features or components, whether or not the other is present. For example, "A and / or B" should be construed as a specific disclosure of (i) A, (ii) B, and (iii) each of A and B, as if each were individually set forth herein.

[0040] As used herein, the term "one or more" can mean 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more, up to any number.

[0041] The terms "and combinations thereof" and "and combinations thereof," respectively, may be used herein following a list of items that are included singly or collectively. For example, components, processes, and / or other items selected from the group consisting of A, B, C, and combinations thereof, is intended to include a set of one or more components that includes one, two, three or more of item A, one, two, three or more of item B, and / or one, two, three or more of item C.

[0042] As used herein, unless otherwise stated, "and" can mean "or" and vice versa. For example, if a feature is described as having A, B, or C, the feature can have A, B, and C, or any combination of A, B, and C. Similarly, if a feature is described as having A, B, and C, the feature can have only one or two of A, B, or C.

[0043] As used herein, when a quantifiable parameter is described as having a value "between" a first value X and a second value Y, it is intended to include parameters having values ​​at least X, less than or equal to Y, and / or at least X and less than or equal to Y. For example, a length from 1 to 10 is intended to include a length of at least 1 (including values ​​greater than 10), a length less than 10 (including values ​​less than 1), and / or values ​​greater than 1 and less than 10.

[0044] As used in this disclosure, the phrase "configured for" may be used interchangeably with, for example, "suitable for," "capable of," "designed for," "adapted for," "made for," and "capable of," depending on the context. "Configured for" does not mean only "specially designed for" in hardware. Alternatively, depending on the context, a "device configured for" may mean that a device is "capable of" operating with another device or component.

[0045] As used herein, the term "threshold" refers to a maximum level, a minimum level, and / or a range of values ​​that correlate to a desired or undesirable state. In some embodiments, a system parameter is maintained above a minimum threshold, below a maximum threshold, within a threshold range of values, and / or outside a threshold range of values, for example, to provide a desired effect (e.g., effective treatment) and / or prevent or otherwise reduce (hereinafter "prevent") an undesirable event (e.g., device and / or clinical adverse event). In some embodiments, a system parameter is maintained above a first threshold (e.g., above a first temperature threshold to provide a desired therapeutic effect on tissue) and below a second threshold (e.g., below a second temperature threshold to prevent undesirable tissue damage). In some embodiments, the thresholds are determined to include a safety margin, for example, taking into account patient variability, system variability, tolerances, etc. As used herein, "above a threshold" means that the parameter is above a maximum threshold, below a minimum threshold, within a threshold range, and / or outside a threshold range.

[0046] As used herein, "room pressure" is intended to mean the pressure of the environment surrounding the systems and devices of the inventive concept. Positive pressure includes pressure above room pressure, or simply a pressure greater than another pressure, such as a positive pressure differential across a fluid path component such as a valve. Negative pressure includes pressure below room pressure, or a pressure less than another pressure, such as a negative pressure differential across a fluid path component such as a valve. Negative pressure may include a vacuum, but does not mean a pressure less than a vacuum. As used herein, the term "vacuum" may be used to refer to a full vacuum or a partial vacuum, or any negative pressure as described above.

[0047] The term "diameter" is used herein to describe non-circular geometric shapes and should be interpreted as the diameter of an imaginary circle that approximates the geometric shape being described. For example, when describing a cross-section, such as a cross-section of a component, the term "diameter" is interpreted as representing the diameter of an imaginary circle having the same cross-sectional area as the cross-section of the component being described.

[0048] As used herein, the terms "major axis" and "minor axis" of a component are the length and diameter, respectively, of an imaginary cylinder of smallest volume that could completely enclose the component.

[0049] As used herein, the term "functional element" should be interpreted to include one or more elements constructed and arranged to perform a function. A functional element may include a sensor and / or a transducer. In some embodiments, a functional element is configured to deliver energy and / or otherwise treat tissue (such as a functional element configured as a therapeutic element). Alternatively or additionally, a functional element (such as a functional element including a sensor) may be configured to record one or more parameters, e.g., patient physiological parameters, patient anatomical parameters (such as tissue shape parameters), patient environmental parameters, and / or system parameters. In some embodiments, a sensor or other functional element is configured to perform a diagnostic function (e.g., collect data used to perform a diagnosis). In some embodiments, a functional element is configured to perform a therapeutic function (e.g., deliver therapeutic energy and / or a therapeutic agent). In some embodiments, the functional element includes one or more elements constructed and arranged to perform a function selected from the group consisting of: delivering energy, extracting energy (e.g., to cool a component), delivering a drug or other agent, manipulating a system component or patient tissue, recording or otherwise sensing a parameter, such as a patient physiological parameter or a system parameter, and one or more combinations thereof. The functional element may include a fluid and / or a fluid delivery system. The functional element may include a reservoir, e.g., an expandable balloon or other fluid-holding reservoir. A "functional assembly" may include an assembly constructed and arranged to perform a function, such as a diagnostic and / or therapeutic function. The functional assembly may include an expandable assembly. The functional assembly may include one or more functional elements.

[0050] As used herein, the term "transducer" is intended to include any component or combination of components that receives energy or any input and generates an output. For example, a transducer may include an electrode that receives electrical energy and distributes the electrical energy to tissue (e.g., based on the size of the electrode). In some configurations, a transducer converts an electrical signal into any output, such as light (such as a transducer including a light-emitting diode or a light bulb), sound (such as a transducer including a piezoelectric crystal configured to deliver ultrasonic energy), pressure (such as an applied pressure or force), thermal energy, cryogenic energy, chemical energy, mechanical energy (such as a transducer including a motor or a solenoid), magnetic energy, and / or a different electrical signal (e.g., different from the input signal to the transducer). Alternatively or additionally, a transducer may convert a physical quantity (such as a change in a physical quantity) into an electrical signal. A transducer may include any component that delivers energy and / or an agent to tissue, such as a transducer configured to deliver one or more of electrical energy to tissue (such as a transducer including one or more electrodes), optical energy to tissue (such as a transducer including a laser, a light emitting diode, and / or an optical component such as a lens or prism), mechanical energy to tissue (such as a transducer including a tissue manipulation element), acoustic energy to tissue (such as a transducer including a piezoelectric crystal), chemical energy, electromagnetic energy, magnetic energy, and combinations of one or more of these.

[0051] As used herein, the term "fluid" may refer to any flowable material, such as a liquid, gas, gel, or material that can be propelled through a lumen and / or opening.

[0052] As used herein, the term "material" can refer to a single material or a combination of two, three, four or more materials.

[0053] It will be understood that certain features of the inventive concepts, which are for clarity described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the inventive concepts, which are for brevity described in the context of a single embodiment, may also be provided separately or in any suitable subcombination. For example, it will be understood that all features set forth in any of the claims (whether independent or dependent) may be combined in any given manner.

[0054] At least some of the drawings and descriptions of the inventive concepts have been simplified to focus on elements relevant for a clear understanding of the inventive concepts, but it should be understood that for the sake of clarity, the omission of other elements that a person skilled in the art would understand may also be part of the inventive concepts, however, because such elements are well known in the art and because they do not necessarily facilitate a better understanding of the inventive concepts, descriptions of such elements are not provided herein.

[0055] The terms defined in this disclosure are used only to describe certain embodiments of the disclosure and are not intended to limit the scope of the disclosure. Terms provided in the singular form are intended to include the plural form unless the context clearly indicates otherwise. All terms used herein, including technical or scientific terms, have the same meaning as commonly understood by those skilled in the relevant field, unless otherwise defined herein. Terms defined in commonly used dictionaries should be interpreted as having the same or similar meaning as the meaning in the context of the relevant technology, and should not be interpreted as having an ideal or exaggerated meaning unless explicitly defined herein. In some cases, the terms defined in this disclosure should not be interpreted as excluding embodiments of the disclosure.

[0056] Provided herein are capacitive micromachined ultrasonic transducers (CMUTs), methods of manufacturing the CMUTs, and devices and systems incorporating these CMUTs. The CMUTs may include an electrode and a plate overlying the electrode to form a cavity. The electrode may include a contoured electrode and / or the plate may include a contoured plate. A voltage applied across the electrode and the plate deflects the plate. The cavity includes a non-uniform cavity space between the plate and the electrode, with the cavity space being largest in a central region of the plate.

[0057] Referring now to FIG. 1, a schematic diagram of a system including a device with at least one capacitive micromachined ultrasonic transducer (CMUT) consistent with the inventive concept is shown. The system 10 of FIG. 1 includes various components, such as one or more devices, shown as device 100. The device 100 may include one or more ultrasonic sensors, such as US sensor 500, as also shown. The device 100 may also include a processing unit 110, and a user interface 120, each as described herein. The device 100 may include a functional element 199, as shown. The functional element 199 may include one or more sensors, one or more transducers, and / or one or more other functional elements. The device 100 may include a consumer electronic device, such as a mobile phone, a tablet, a personal computer, and / or other electronic device. In some embodiments, device 100 includes a medical device, such as a medical device selected from the group consisting of a device that delivers ultrasonic energy to tissue (e.g., to stimulate tissue, ablate tissue, and / or image tissue), a drug delivery device, a cardiac pacing device, a neuroablation device, and combinations thereof. In some embodiments, device 100 includes a medical device configured to deliver ultrasonic energy (e.g., via one or more CMUTs of CMUT 510), where the ultrasonic energy is configured to image tissue, ablate tissue, or both image and ablate tissue.

[0058] The US sensor 500 of the inventive concept may include one or more CMUT components (or CMUT "cells" herein), of which a CMUT 510 is shown here. The CMUT 510 and / or other components of the sensor 500 may be constructed and arranged as described with reference to any of FIG. 1, FIG. 1A, or FIG. 2-50. The CMUT 510 may be fabricated using one or more of an oxidation process, an etching process, and / or a doping process as described herein. In some embodiments, the US sensor 500 includes an electronic assembly and / or other components, i.e., a driving circuit 520, operably connected to the CMUT 510. The driving circuit 520 may include a power source, a signal generator, a data converter (e.g., an analog-to-digital data converter and / or a digital-to-analog data converter), and / or other components configured to operate the CMUT 510 in various operating modes described herein. In some embodiments, the sensor 500 includes an array of two or more CMUTs 510, i.e., an array 5010. The CMUT 510 may be configured for use in submerged applications (e.g., where the CMUT 510 includes at least one or more sealed CMUT transducers) and / or in air-coupled applications (e.g., where the CMUT 510 includes at least one or more air-coupled CMUT transducers).

[0059] Capacitive micromachined ultrasound transducers (CMUTs) have emerged as an alternative to piezoelectric-based ultrasound transducers in a variety of applications, including medical imaging, therapy, high intensity focused ultrasound (HIFU), chemical detection, and air-coupling applications. Currently available CMUT transducers include a combination of planar plates and planar electrodes, which are widely used in CMUT-based components. The plates of CMUTs are highly deflected when large direct current (DC) and / or alternating current (AC) voltages are applied to achieve high sensitivity and / or high output voltage. When the plates are deflected, only the central area, a small portion of the entire plate, experiences the maximum electric field. This limitation reduces the electromechanical coupling efficiency, limiting both the transmission and reception sensitivity.

[0060] In some embodiments, device 100 includes a processing unit 110. Processing unit 110 may include at least one microprocessor, computer, and / or another electronic controller, here shown as processor 111. Processing unit 110 may also include one, two, or more algorithms, here shown as algorithm 115. Algorithm 115 may include one or more machine learning, neural network, and / or other artificial intelligence algorithms (herein "AI algorithms"). Processing unit 110 may include one or more memory storage modules, shown as memory 112, for example, to store instructions for executing algorithm 115 and / or to store other information of system 10 (e.g., calibration and / or other manufacturing information, and / or usage information of system 10). Processor 111, via algorithm 115, may execute one or more processes described herein, e.g., processes executed in response to one or more commands entered by a user into system 10 (e.g., via user interface 120 described herein). In some embodiments, the algorithm 115 (e.g., an AI algorithm) is configured to adjust the drive signal generated by the drive circuit 520 to, for example, optimize or otherwise alter the performance of the CMUT 510 (such as a CMUT 510 including one or more CMUTs 510). In some embodiments, the algorithm 115 is configured to analyze one or more parameters of a patient receiving ultrasound energy from the CMUT 510, for example, one, two, or more physiological parameters recorded by a functional element 199 including one, two, or more sensors. In these embodiments, the algorithm 115 may be configured to adjust the drive signal generated by the drive circuit 520 to, for example, improve an image provided by the device 100 and / or improve a treatment. The processing unit 110 may receive one or more signals (such as signals including data), for example, a signal received from the US sensor 500. The processing unit 110 may be configured to perform one or more mathematical operations based on the received signals to generate a result.The processing unit 110 may be configured to perform and / or facilitate the performance of one or more functions of system 10 (herein referred to as "performing" either or both), such as energy delivery (such as delivery of ultrasonic energy via the US sensor 500, such as to ablate or stimulate tissue), data collection (such as creating and / or collecting image data), data analysis, signal processing, procedure planning, and / or other functions (herein referred to individually or collectively as "functions of system 10").

[0061] Device 100 may include one, two, or more interfaces for providing information to and / or receiving information from a user of system 10, shown here as user interface 120. User interface 120 may include one, two, or more user input and / or user output components. For example, user interface 120 may include a joystick, keyboard, mouse, touch screen, and / or another human interface device, shown here as user input device 121. In some embodiments, user interface 120 includes a display (e.g., a touch screen display), such as display 122, also shown. In some embodiments, processor 111 may provide a graphical user interface, GUI 123, presented on and / or provided by display 122. The user interface 120 may include input and / or output devices selected from the following group: speakers, indicator lights such as LED displays, tactile feedback devices, foot pedals, switches such as momentary switches, microphones, cameras, for example where the processor 111 enables eye tracking and / or other input via image processing, and combinations thereof.

[0062] The CMUT 510 is described herein with reference to the corresponding orientation shown in the figures. For example, when referring to the bottom of the CMUT 510, the portion of the CMUT 510 disposed toward the bottom of the page is described. The CMUT may be comprised of a "plate" suspended above a "bottom electrode" with a space therebetween (e.g., a vacuum gap and / or a fluid-filled space). For example, the CMUT 510 may include a bottom electrode 511 (also referred to herein as a substrate 511), which is a first conductive film, and a plate 512 (also referred to herein as a top electrode 512), which is a second conductive film. The bottom electrode 511 and the plate 512 may be axially separated and define a space therebetween, a cavity 513 (e.g., a cavity maintained at a vacuum or other negative pressure compared to the environmental pressure). In some embodiments, a dielectric film 514, which is an insulating film, is disposed between the bottom electrode 511 and the plate 512. For example, the dielectric film 514 may be disposed on the substrate 511, the dielectric film 514 may be disposed on the plate 512, or may include two dielectric films 514, a first film 514a disposed on the substrate 511 and a second film 514b disposed on the plate 512. In an embodiment with a single dielectric film 514, the film 514 may include a thickness of at least 5 nm or 10 nm, and / or a thickness of 800 nm, 600 nm, or 400 nm or less, for example a thickness of about 200 nm. In an embodiment with a first dielectric film 514a (e.g., disposed on the substrate 511) and a second dielectric film 514b (e.g., disposed on the plate 512), the film 514a may include a thickness of at least 5 nm or 10 nm, and / or a thickness of 800 nm, 600 nm, or 400 nm or less, and the dielectric film 514b may include a thickness of at least 2 nm or 5 nm, and / or a thickness of 250 nm or 150 nm or less. Either or both films may include silicon dioxide. In some embodiments, the dielectric film 514 includes two films with a total thickness of 1050 nm, 800 nm, 600 nm, or 400 nm or less. Each dielectric film 514 may include a minimum thickness (such as at least 5 nm) to, for example, reduce field emissions (e.g., electrons passing through the cavity 513). In some embodiments, the plate 512 is a shaped plate 512.S , which includes a plate 512 that includes a shaped ("shaped," "contoured," and / or "non-planar") shape, as described herein. In some embodiments, the bottom electrode 511 is a shaped bottom electrode 511 S (For example, molded substrate 511 S 514), which includes a bottom electrode 511 that includes a shaped ("shaped," "contoured," and / or "non-planar") shape, as described herein. In some embodiments, the dielectric film 514 is a shaped dielectric film 514 S ("Forming film 514 S "), which includes a dielectric film 514 that includes a shaped (also referred to as "shaped," "contoured," and / or "non-planar") shape, as described herein. For example, the dielectric film 514 may be disposed on the top surface of the bottom electrode 511 (at the bottom of the cavity 513) or on the bottom surface of the plate 512 (at the top of the cavity 513). In some embodiments, the axial space between the bottom electrode 511 and the plate 512 is maintained by one or more supports, as shown, supports 515. The supports 515 may include a hollow ring (such as a circular ring) that may be disposed along the periphery of the electrode 511 and the plate 512, such that the cavity 513 is disposed within the supports 515.

[0063] The substrate 511 may be composed of one, two, or more of a variety of similar and / or different materials, such as silicon and / or glass. In some embodiments, the substrate 511 includes a thickness that is less than or equal to 70%, 60%, 50%, and / or 40% of the length of the smallest wavelength of the operating frequency of the associated CMUT 510. In some embodiments, the substrate 511 includes a thickness that is less than 50% of the length of the smallest wavelength of the operating frequency, e.g., to reduce the impact of acoustic resonances in the substrate on the performance of the CMUT 510.

[0064] The cavity 513 may include one, two, or more geometric cross-sectional shapes, such as a circle, an ellipse, a rectangle, a square, a hexagon, a triangle, and combinations of one, two, or more thereof. The cavity 513 may include a height of at least 10 nm, 25 nm, or 40 nm, and / or a height of 5 μm, 7 μm, and / or 10 μm or less. In some embodiments, the cavity 513 includes a height of at least 100 nm, and / or a height of 500 nm or less.

[0065] The dielectric film 514 may include one, two, or more of a variety of similar and / or different materials, such as silicon oxide and / or silicon nitride (e.g., a multi-layer structure includes both silicon nitride and silicon oxide). The dielectric film 514 may include a material having a high dielectric constant value ("k value"), such as hafnium oxide. The dielectric film 514 may include a thickness that is determined such that the maximum electric field experienced by the dielectric film 514 during operation is a particular percentage of the dielectric strength of the film 514, for example, at least 15%, 22%, or 30% of the dielectric strength of the film 514, and / or no more than 40%, 50%, 60%, 70%, 77%, or 85% of the dielectric strength of the film 514.

[0066] The supports 515 may include one, two, or more of a variety of similar and / or different materials, such as silicon oxide and / or silicon nitride, in some embodiments, the first support 515a includes a first material and the second support 515b includes a second material that is different from the first material.

[0067] Plate 512 may be composed of one, two, or more of a variety of similar and / or different materials, such as silicon, silicon nitride, and / or diamond. In some embodiments, plate 512 comprises a thickness of at least 0.2%, 0.5%, or 1% of the width of cavity 513, and / or a thickness of no more than 20%, 30%, or 40% of the width of the cavity.

[0068] In some embodiments, the plate 512 includes two or more films, such as at least one conductive film (e.g., a film forming the top electrode) and one or more non-conductive films. For example, the plate 512 may include a stack of two non-conductive films with a conductive film sandwiched between them. The edges of the plate 512 may be attached to supports 515. The plate 512 is configured to deflect axially toward and / or away from the bottom electrode 511. In some embodiments, the plate 512 deflects in response to a driving electrical signal applied between the bottom electrode 511 and the top electrode 512 (e.g., when the CMUT 510 is configured in a "transmit mode"). As used herein, a signal (e.g., an AC signal, a DC signal, and / or a signal including AC and DC components) applied (e.g., by the processing unit 110) between the top plate 512 and the bottom electrode 511 may be described as being applied "across" the CMUT 510. Alternatively, or in addition, an electrical signal may be generated (e.g., received by the processing unit 110) between the lower electrode 511 and the upper electrode 512 because one or more pressure waves received by the CMUT 510 cause the plate 512 to deflect axially (e.g., vibrate relative to the lower electrode 511 when the CMUT 510 is configured in “receive mode”).

[0069] The performance of the CMUT 510 may be defined by one or more metrics, such as transmit sensitivity, receive sensitivity, and / or maximum output pressure. The transmit sensitivity may be defined as the pressure output per voltage applied across the CMUT 510. The receive sensitivity may be defined as the output current from the CMUT 510 (e.g., output current per Pascal of incident pressure) relative to the incident pressure of the pressure wave that causes actuation (e.g., deflection) of the plate 512. The maximum output pressure is defined as the maximum pressure that the CMUT 510 can generate when operating in a transmit mode. As described herein, the edges of the plate 512 may be fixed to the supports 515, such that there is zero axial movement at the edges of the plate 512 and the axial movement of the plate 512 is maximum at the center of the CMUT 510 (farthest from the fixed edge). The maximum output pressure of the CMUT (such as the CMUT 510) may be limited by the height (e.g., “gap height”) of the cavity 513.

[0070] In some embodiments, the maximum output pressure of the CMUT 510 may be increased if a larger portion of the plate 512 is displaced (e.g., a larger average displacement for the same maximum displacement) when a signal is applied to the CMUT 510. The average displacement of the plate 512 is determined by the shape and / or properties of the material of the CMUT 510, as described herein. In some embodiments, the CMUT 510 includes a contoured (e.g., including one, two, or more stepped, curved, and / or other non-planar portions) electrode, i.e., a shaped electrode 511. S , which causes the average displacement of the plate 512 to increase due to the increased electrostatic force applied to the outer portions of the plate 512 relative to the center of the plate 512. Alternatively or additionally, the CMUT 510 may include a contoured (including one, two or more stepped, curved, and / or other non-planar portions) plate, i.e., a shaped plate 512. Sto similarly achieve an increase in these electrostatic forces on plate 512. In some embodiments, electrode 511 and / or plate 512 include at least one planar portion, at least one concave portion, and / or at least one convex portion. S This allows for a lower gap height near the edges of plate 512 relative to the center of plate 512. This lowering of the gap height increases the electric field near the edges of plate 512, resulting in higher electrostatic forces, e.g., at least 2%, 5%, 20%, 25%, and / or 50% increase in electrostatic forces compared to a similar component (e.g., a component of similar size or construction material) that includes a non-contoured (e.g., flat) shape. Lowering the gap height may improve transmit sensitivity (e.g., at least 2%, 5%, 10%, 25%, and / or 50% increase) due to an increase in average plate displacement per volt. Lowering the gap height may also improve receive sensitivity (e.g., at least 2%, 5%, 10%, 25%, and / or 50% increase) due to a larger change in capacitance due to movement of plate 512. The increased transmit and receive sensitivity of these geometric designs of the inventive concept are achieved without physically limiting the maximum displacement of the plate 512 and therefore the maximum output pressure of the CMUT 510 (e.g., in comparison to a CMUT geometry including a planar electrode 511 and a planar plate 512, this geometry provides improved sensitivity with increasing gap height, but at the expense of reduced maximum output pressure). Examples of assemblies of CMUT 510 and other components including plate 512 with shaped profiles are described with reference to the various figures provided and described herein.

[0071] Molded Plate 512 S and / or molded substrate 511 S Each of the forming plates 512 may include a contoured (molded) profile, including a "stepped profile," for example, a stepped profile that includes at least two levels (such as at least two steps), at least three levels, or at least four levels. S4B, 5A, 8A, 10A, 22A, 24A, 26A, 28A, and / or other references and descriptions herein (e.g., stepped portion 5123 described herein). S 7B, 9B, 12B, 23B, 25B, and / or other references herein. S and / or molded substrate 511 S One or more (such as all) of the steps include a thickness that is at least 5% or at least 10% of the gap height of the cavity 513 of the CMUT 510. In some embodiments, the molded plate 512 S and / or molded substrate 511 S One or more (such as all) of the steps include a thickness that is less than or equal to 50%, 60%, or 70% of the thickness of the plate 512. S and / or molded substrate 511 S One or more (such as all) steps of the process may include one, two, or more of a variety of similar and / or different materials, such as silicone. S and / or molded substrate 511 S Each step includes a forming plate 512 S and / or molded substrate 511 Smay include the same or different materials as the remaining portion. In some embodiments, the transition between at least one pair of steps includes a smoothed transition and / or a rounded transition. In some embodiments, two or more steps have substantially equal widths. In some embodiments, two or more steps have substantially equal widths, but the central step (e.g., the step closest to the center of the cavity 513) has a width that is approximately twice the width of two or more steps having substantially equal widths. In some embodiments, one or more "corners" of one or more steps (e.g., corners near the center of the cavity 513) are proximal to and disposed immediately below the maximum deflection profile of the plate 512, such that these steps produce a large effect without interfering with the deflection of the plate 512.

[0072] Forming plate 512 S and / or forming substrate 511 S each of which may include a contoured (formed) profile that includes a "tapered profile" that includes one or more portions that are tapered or have an inclined shape. In some embodiments, the forming plate 512 S includes tapered portions (e.g., tapered portion 5124 described herein) constructed and arranged as described in reference to FIGS. 4C, 5B, 8B, 10B, 22B, 24B, 26B, 28B, and / or elsewhere herein. Alternatively or additionally, the substrate 511 S may include tapered portions (e.g., tapered portion 5114 described herein) constructed and arranged as described in reference to FIGS. 7C, 9C, 12C, 23C, 25C, and / or elsewhere herein. The tapered portions of the forming plate 512 S and / or the forming substrate 511 S may each include the same or different materials as the remaining portion of the forming plate 512 S and / or the forming substrate 511 S .

[0073] Forming plate 512 S and / or forming substrate 511 SEach of the shaped plates 512 may include a contoured (shaped) profile that includes a "curved profile" that includes one or more portions of a curved shape. S 4D-E, 5C-D, 8C-D, 10C-D, 22C-D, 24C-D, 26C-D, 28C-D, and / or other references herein, including curved portions (e.g., curved portions 5125 as described herein). S 7D-E, 9D-E, 12D-E, 23D-E, 25D-E, and / or other parts of the present specification (e.g., curved portion 5115, as described herein). S and / or molded substrate 511 S The curved portions of the plates 512 are S and / or molded substrate 511 S The inner wall of the inner periphery may comprise the same material as the remainder of the inner periphery or a different material.

[0074] In some embodiments, the CMUT 510 increases the average displacement of the plates 512 (e.g., by at least 2%, 5%, 10%, 25%, and / or 50%) based on the geometry (e.g., thickness) and / or physical properties (e.g., dielectric constant) of the dielectric film 514. Examples of CMUT 510 components that include variations in the dielectric film 514 are described with reference to Figures 31-35B and elsewhere herein.

[0075] In addition, referring to Figures 1A and 1B, cross-sectional views of two examples of current (e.g., commercially available) CMUT structures consistent with the inventive concept are shown. Figure 1A shows a CMUT 510', which includes a substrate, i.e., substrate 511, which includes a conductive material (e.g., doped silicon), and an insulating film, i.e., a dielectric film 514, which is disposed on the substrate 511 and includes a dielectric material (e.g., silicon nitride). A support 515 extends vertically from the dielectric film 514, which also includes a dielectric material (e.g., silicon nitride). A plate 512 is disposed on the support 515, and a cavity 513 is formed between the dielectric film 514 and the plate 512. The plate 512 of the CMUT 510' includes a multi-layer structure, and includes a first conductive film, film 5121, which includes a conductive material (e.g., aluminum), and a first insulating film, film 5122, which includes a dielectric material (e.g., silicon nitride). The membrane 5121 may include a structure and arrangement to avoid significant impact of the membrane 5121 on the plate 512. In some embodiments, the membrane 5121 includes a thickness that is less than 50%, 40%, or 33% of the thickness of the plate 512. The membrane 5121 may include one, two, or more different materials, such as similar materials and / or different materials. In some embodiments, the membrane 5121 includes one, two, or more materials selected from the following group: aluminum, titanium, chromium, gold, aluminum with copper and / or silicon (e.g., up to 2% copper and / or silicon), indium tin oxide, and / or other transparent conductive materials, and combinations thereof. The membrane 5121 may include a multi-layer structure, such as a titanium layer and an aluminum layer (e.g., as a diffusion barrier). The membrane 5122 may include a thickness of at least 0.2%, 0.5%, or 1% of the width of the cavity 513. The membrane 5122 may include one, two, or more different materials, such as similar and / or different materials. The membrane 5122 may include silicon nitride.

[0076] FIG. 1B shows another embodiment of a CMUT 510″, which includes a substrate 511 including a conductive material (such as doped silicon). Also included is a dielectric film 514 and a support 515, each including a dielectric material (such as silicon oxide) as shown. A plate 512 is disposed on top of the support 515, thereby forming a cavity 513 between the dielectric film 514 and the plate 512. The plate 512 of the CMUT 510″ includes a multi-layer structure and includes a first conductive film, film 5121a, including a conductive material (such as doped silicon), and a second conductive film, film 5121b, including another conductive material (such as aluminum).

[0077] 1A and 1B show two of many possible structures for a CMUT 510 in accordance with the inventive concept. As described herein, each layer and / or component of the CMUT 510 can include one or more materials, portions, and / or can include various shapes. For example, the CMUT 510 may include one, two, or more of the inventive concepts described herein, such as one, two, or more of the following component configurations selected from the following group: contoured (e.g., non-planar) dielectric film, dielectric film having a high k (i.e., relative dielectric constant) value, such as k values ​​greater than 5, 10, 100, 500, 1000, or 5000, combinations of dielectric materials, such as standard dielectric materials and / or combinations with dielectric materials having high k values, such as k values ​​greater than 3.8, 5, 10, 100, 1000, or 5000, shaped plates, shaped bottom electrodes, piston components, combinations of shaped plates and dielectric film and / or shaped bottom electrodes, vented cavities, cavities including fluid trenches, and combinations thereof. Each of these configuration options may be configured to operate in a collapse mode, a conventional mode, a variable voltage mode, such as a low voltage mode, and / or other CMUT operating modes as described herein.

[0078] In some embodiments, the inventive CMUT 510 is configured to operate in a "conventional mode." In the conventional mode, the plate 512 is supported by the support 515 and vibrates like a drum head without touching the bottom surface of the cavity 513. Alternatively or additionally, the CMUT 510 may be configured to operate in a "collapse mode." In the collapse mode, a central portion of the plate 512 contacts the bottom surface of the cavity 513 (e.g., the plate 512 is pulled into contact with the bottom of the cavity 513 by an applied DC voltage). During operation, the portion of the plate 512 between the support 515 and the contacting central portion (e.g., the "ring" portion of the plate 512) vibrates with the central portion in contact with the bottom of the cavity 513.

[0079] In some embodiments, the CMUT 510 includes a "vented CMUT," e.g., a CMUT that includes one or more openings between the cavity 513 and the surrounding environment, i.e., vents 516 as described herein. In some embodiments, the cavity 513 of the vented CMUT 510 includes one or more trenches or other fluid paths 517 that may be constructed and arranged to manipulate a fluid (e.g., air) within the cavity 513 upon actuation of the CMUT 510. Various embodiments of the CMUT 510, including the vented CMUT, are described with reference to FIGS. 21A-28D, and elsewhere herein. An embodiment of the CMUT 510 that includes a trench 517 that includes one or more trenches and / or other fluid paths (referred to herein as a "trench" or "trenches") are described with reference to FIGS. 23A-28D, and elsewhere herein.

[0080] The vent 516 may include one, two, or more similar and / or different cross-sectional shapes, such as circles, ovals, rectangles, squares, triangles, and / or combinations thereof. In some embodiments, the vent 516 includes a major axis that is less than 10%, 7.5%, 5.0%, 2.5%, and / or 1.5% of the length of the major axis of the CMUT 510 (e.g., the vent 516 includes a circle with a diameter that is less than 10%, 7.5%, 5.0%, 2.5%, and / or 1.5% of the length of the major axis of the CMUT 510).

[0081] Trenches 517 may include one or more trenches or other fluid paths that are at least 0.5 μm, 1.0 μm, or 2 μm deep, and / or no greater than 15 μm, 25 μm, or 35 μm deep.

[0082] In some embodiments, the CMUT 510 is configured to operate in a "low voltage mode." For example, a pull-in voltage of 100V or 50V may be applied to configure the CMUT 510 in collapse mode (e.g., for typical collapse voltages above 100V). The CMUT 510 may operate in low voltage mode when the device 100 includes a portable device (e.g., a device configured to operate in a low power mode). In some embodiments, the CMUT 510 includes a shaped bottom electrode 511. S , a shaped upper electrode (e.g., a shaped plate 512 S ), and / or a shaped dielectric film 514 configured (e.g., enabling) the CMUT 510 to operate in a low voltage mode. S Includes.

[0083] In some embodiments, the CMUT 510 is configured to operate at 5 MHz with a pull-in voltage of 90 V. In these embodiments, the CMUT 510 may include one or more specifications selected from the following group: a plate 512 with a radius of 29 μm, a plate 512 with a silicon layer thickness of 1.7 μm, a plate 512 with an aluminum layer thickness of 300 nm, a gap height of 230 nm, a dielectric film 514 with a thickness (e.g., oxide insulator thickness) of 220 nm, and combinations thereof. For example, a CMUT with one or more (e.g., all) of these specifications may have a transmit sensitivity (e.g., 80% of pull-in) of at least 9.9 kPa / V.

[0084] In some embodiments, the CMUT 510 is configured to operate at 5 MHz with a pull-in voltage of 45 V. In these embodiments, the CMUT 510 may include one or more specifications selected from the following group: a plate 512 with a radius of 29 μm, a plate 512 with a silicon layer thickness of 1.7 μm, a plate 512 with an aluminum layer thickness of 300 nm, a gap height of 160 nm, a dielectric film 514 with a thickness (e.g., oxide insulator thickness) of 100 nm, and combinations thereof. Simulations performed by applicants have shown that this CMUT configuration achieved a sensitivity of 12.1 kPa / V at 5 MHz and a bias voltage of 36.2 V (80% of pull-in).

[0085] In some embodiments, the CMUT 510 of the inventive concept is configured for use in airborne and / or submerged applications (e.g., one or more devices 100 including one or more CMUTs 510 are configured for use in airborne and / or submerged applications). For example, the CMUT 510 may be used in harsh environments, such as high pressure, high temperature, and / or toxic environments, such as inside gas pipelines, in chemical facilities, and / or in aerospace applications, spacecraft and / or vehicles, structures, or equipment designed for use on Mars or other exoplanets, etc.

[0086] In some embodiments, the CMUT 510 of the inventive concept is configured to deliver HIFU energy. For example, the plate 512 may include a relatively thick metal layer (e.g., for low current heating), such as a layer of about 400 nm. In these embodiments, the CMUT 510 may be configured to provide a minimum output voltage (e.g., a minimum value that depends on the operating frequency). The CMUT 510 may be configured to operate with a pull-in voltage of 200V or less, making it compatible with standard electronic components such as switches and preamplifiers. In some embodiments, the CMUT 510 is configured to run at a low voltage (e.g., a voltage less than 200V), resulting in lower electric fields during use (e.g., reduced loading on the components of the CMUT 510) and reduced requirements for the transmit and receive electronics attached to the CMUT 510.

[0087] The shape of the plate 512 affects the mass and spring constant of the plate 512, and therefore the applicable operating frequency and operating bandwidth. The second harmonic of the plate 512 may limit the bandwidth of the CMUT 510 and contribute to the nonlinearity of the CMUT response to the excitation voltage. Thus, increasing the frequency of the second harmonic relative to the fundamental frequency may increase the bandwidth of the CMUT 510 (e.g., at least a 2%, 5%, 10%, 25%, and / or 50% increase) and / or reduce the nonlinearity of the CMUT response (e.g., at least a 2%, 5%, 10%, 25%, and / or 50% decrease), both of which are often desired. The shape (e.g., cross-sectional shape) of the plate 512 may be configured to increase the second harmonic frequency (e.g., at least a 2%, 5%, 10%, 25%, and / or 50% increase) while keeping the fundamental frequency constant.

[0088] The CMUT 510 may include a convex lens (e.g., with a speed of sound lower than the speed of sound in tissue) configured to focus the ultrasound beam in elevation (e.g., a 1D array). The convex lens may include a thickness of several times the wavelength of sound used and is limited by the attenuation of the ultrasound passing therethrough. This attenuation results in heating of the lens and also reduces the output pressure of the CMUT 510. In some embodiments, the CMUT 510 includes a Fresnel lens with a reduced thickness compared to a corresponding convex lens, thereby relatively reducing the attenuation of the lens (e.g., at least a 2%, 5%, 10%, 25%, and / or 50% decrease) and increasing the output pressure (e.g., at least a 2%, 5%, 10%, 25%, and / or 50% increase).

[0089] In some embodiments, the US sensor 500 is configured to operate in a closed loop manner, for example when the US sensor 500 includes a CMUT 510 and is constructed and arranged to provide active feedback (e.g., to the processing unit 110) related to the position of the plate 512 during operation of the CMUT 510. A challenge with CMUTs is that the sensitivity of the plate displacement to voltage is highly nonlinear. The plate displacement is much more sensitive to changes in voltage when operating at high voltages. This is the case for both AC drive voltages and DC bias voltages. This sensitivity makes it difficult to move the plate across the full gap during transmission (e.g., when operating at a voltage close to the voltage that transitions the CMUT 510 into collapse mode), which maximizes the output pressure. Also, in receive mode, it is difficult to hold the plate displacement very close to collapse without going into collapse. In some embodiments, operating multiple CMUTs 510 in an array (e.g., array 5010 described herein) close to collapse mode without one or more CMUTs 510 unintentionally collapsing is difficult due to variations between the CMUTs 510 in the array. To avoid these problems, the system 10 can include feedback on the position of the plate 512, which improves control of the plate displacement (e.g., at least 2%, 5%, 10%, 25%, and / or 50% improvement in control accuracy of the plate displacement), thus improving performance and avoiding problems (e.g., avoiding collapse). The feedback signal can be provided by several different configurations of the CMUTs 510. The feedback signal can provide a measurement of the plate displacement relative to the gap height. In some embodiments, the feedback signal can be used to set the DC bias voltage very close to the collapse voltage to maximize the receive sensitivity when the CMUTs 510 are operating in receive mode. Additionally or alternatively, a feedback signal may be used to set the AC drive signal such that the maximum plate displacement is a large percentage of the gap height, resulting in a higher output pressure.

[0090] In airborne applications, the bandwidth of the CMUT 510 may be smaller than in non-airborne applications (e.g., submerged applications), requiring better tuning of the resonant frequency and operating frequency of the device in which the CMUT 510 is incorporated. In these applications, the system 10 may track the resonant frequency and transmit and receive using the optimal frequency. The system 10 may be configured to transmit at the shorted resonance and receive at the open resonance of the CMUT 510. The operating frequency of the CMUT 510 may be changed in real time (e.g., during use and / or during a calibration procedure) via a spring softening effect caused by changing the DC bias voltage. In some embodiments, multiple CMUTs 510 may be implemented to operate in groups (e.g., pairs) of CMUTs 510, where each CMUT 510 in the group is configured to operate as a transmitter or a receiver, but not both. In these embodiments, each CMUT510 in a transmitter and receiver group may be configured to operate at the same frequency, and the transmit and receive sensitivities may be optimized for each of the CMUT510 in one or more transmitter configurations and the CMUT510 in one or more receiver configurations at the operating frequency. Because the output impedance of the transmitter is low, the CMUT510 operating as a transmitter enhances performance at short-circuit resonance. The input impedance of the receiver is high (e.g., compared to the output impedance of the transmitter), and reception is often optimal at an open-resonance frequency. Due to the narrow bandwidth, the DC bias may be adjusted for a single CMUT510 configured for both transmit and receive to operate at a frequency with the largest dynamic range. When multiple CMUT510 are arranged in a group including CMUT510 configured to transmit or receive (i.e., not both transmit and receive as described above), the operation of each may be performed at the same frequency, and the structure and arrangement of each transmitter CMUT510 and receiver CMUT510 may be optimized for operation at that frequency.

[0091] The CMUT 510 may be operated at a wide range of frequencies (e.g., drive frequencies or other operating frequencies). In some embodiments, the CMUT 510 is operated at one or more frequencies that are set based on the particular application in which the CMUT 510 is used, such as the particular application in which the device 100 or another system 10 component is used. In some embodiments, the system 10 includes one or more CMUTs 510 operated at a frequency of at least 5 MHz and / or at frequencies of 10 MHz or less. CMUTs 510 including vacuum gaps (e.g., unvented cavities as described in FIG. 4A and elsewhere herein) may be configured to operate at frequencies of at least 10 kHz, 250 kHz, or 500 kHz and / or at frequencies of 50 MHz or less than 100 MHz. CMUTs 510 including vented arrangements (e.g., for operation in airborne applications as described in reference to FIGS. 21A-28D and elsewhere herein) may be configured to operate at frequencies of at least 20 kHz and / or at frequencies of 500 kHz or less.

[0092] In some embodiments, the US sensor 500 (such as the CMUT 510) includes a sensing electrode (e.g., in addition to the lower electrode 511 and the plate 512), which is configured to provide a signal (e.g., to the processing unit 110) related to the position of the plate 512, for example, as described herein with reference to FIG. 2. The sensing electrode may be used in a closed-loop active feedback mode to adjust the AC or DC voltage. Alternatively, or additionally, the sensing electrode may be used for periodic calibration of the US sensor 500, for example, calibration performed (e.g., automatically by the system 10) at least once a week, once a day, once an hour, once a minute, once a second, 5 times a second, or 50 times a second. For example, an AC voltage may be applied in increments of increasing amplitude while the signal from the sensing electrode is measured. The displacement of the plate 512 as a function of the AC voltage is nonlinear, and the shape of the nonlinear curvature may be used as a measure of the plate displacement as a percentage of the gap height.

[0093] In some embodiments, the US sensor 500 includes a calibration circuit 530, which is one or more components configured to provide one or more signals used to calibrate the sensor 500. In some embodiments, the calibration circuit 530 is configured to calibrate the pull-in voltage of one or more CMUTs 510. The pull-in voltage may vary across an array of CMUTs 510, for example due to dimensional non-uniformity of the CMUTs 510 across the array. A self-calibrating structure (such as the calibration circuit 530) may be included to measure the pull-in voltage of one or more CMUTs 510, so that the system 10 (e.g., via the algorithm 115) may adjust the DC bias and / or transmit voltage. In some embodiments, the calibration structure is configured to provide an estimate of the pull-in voltage of one or more CMUTs 510 in the array based on the measured pull-in voltage of the calibration structure. In some embodiments, an array of CMUTs 510 can include one, two, or more calibration structures, each configured to provide an estimate of the pull-in voltage of one or more CMUTs 510 (e.g., CMUTs 510 proximate to the calibration structure in the array). In some embodiments, the calibration circuit 530 includes a string of CMUTs with different gap heights and / or radii. The strings of CMUTs can be connected in parallel and the capacitance versus voltage of the CMUTs can be measured. The system 10 can be configured to detect a jump in capacitance each time a CMUT "pull-ins." The voltage of each capacitance jump can be fitted to a model to extract device parameters (e.g., gap height). Alternatively or additionally, a single design calibration structure can be used to measure the collapse voltage of one or more CMUTs 510 of the array.

[0094] In some embodiments, the CMUT 510 includes one or more support structures, as shown, piston 518. The piston 518 and piston-based CMUT 510 may be constructed and arranged as described with reference to Figures 7, 8, 9, 10, 25, 26, 27, 28, 47, and 48. The piston 518 may be configured to make a portion of the plate 512 stiffer, such that bending of the plate 512 occurs primarily in the portion of the plate 512 that is not supported by the piston 518. This stiffness makes the plate 512 "piston-like," increasing the average displacement of the plate 512 relative to its maximum displacement, which may be used to increase the sensitivity and maximum output pressure of the CMUT 510. The piston 518 may include one, two, or more components including one, two, or more of a variety of similar and / or different materials, such as silicon (e.g., silicon deposited by chemical vapor deposition), aluminum, titanium, chromium, tungsten, and / or gold. In some embodiments, the piston 518 comprises a thickness that is at least 20%, 35%, or 50% of the thickness of the plate 512, and / or a thickness that is no greater than 5, 7, or 10 times the thickness of the plate 512. In some embodiments, when the CMUT 510 is arranged to operate in a non-collapse mode (e.g., as described with reference to FIGS. 7 and 8), the piston 518 may comprise a width that is at least 15%, 22%, or 30% of the width of the plate 512, and / or a width that is no greater than 80%, 87%, or 95% of the width of the plate 512. In some embodiments, when the CMUT 510 is arranged to operate in a collapse mode (e.g., as described with reference to FIGS. 9A-9E), the piston 518 may comprise a width that is at least 5%, 10%, or 15% of the width of the plate 512, and / or a width that is no greater than 25%, 32%, 40%, 44%, or 47% of the width of the plate 512.

[0095] 2, a top view of a plate of a CMUT including a sensing electrode is shown, consistent with the inventive concepts. In some embodiments, the CMUT 510 includes a third electrode, a sensing electrode 5127 (e.g., in addition to the top and bottom electrodes). The sensing electrode 5127 may be located on the top or bottom of the CMUT 510, such as when the sensing electrode 5127 is located near the center of the plate 512 as shown. The sensing electrode 5127 may include an area of ​​20%, 30%, or 40% or less of the area of ​​the cavity 513. In some embodiments, the sensing electrode 5127 is electrically isolated from the plate 512 and / or the bottom electrode 511 of the CMUT 510 (e.g., when the sensing electrode 5127 is located on the top or bottom of the CMUT 510, respectively). For example, the plate 512 may include a segmented plate including one or more channels, as shown, in which the sensing electrode 5127 and conductors (also referred to as "traces") operably connected (e.g., electrically connected) to the sensing electrode 5127 may be disposed. In some embodiments, the sensing electrode 5127 is small relative to the top and / or bottom electrodes of the CMUT 510 (e.g., the bottom electrode 511 and / or the plate 512 configured to actuate the CMUT 510 to transmit and / or receive signals). In some embodiments, the sensing electrode 5127 generates a signal (e.g., a current) that depends on the displacement of the plate 512. This signal may be used as a feedback signal to control a DC bias and / or a transmit voltage on the electrode. In some embodiments, the plate 512 includes a portion including a nitride, carbide, diamond, and / or other dielectric material. In some embodiments, the sensing electrode 5127 is disposed at the bottom of a cavity of the CMUT 510 (e.g., the cavity 513 is not shown, but is described herein).For example, the sensing electrode 5127 may be disposed within the cavity if the CMUT 510 includes a relatively large transducer (e.g., there is a relatively large amount of room within the cavity to create an electrode pattern), such as when the CMUT 510 is configured as an air transducer (e.g., includes a large transducer, such as a transducer whose major axis (e.g., diameter) typically exceeds 0.5 cm, or exceeds 1 cm). For example, air transducers used in ranging applications typically operate in the range of 40 kHz to 100 kHz. At these frequencies, the wavelengths of ultrasound are 8.5 mm and 3.4 mm, respectively. For a single CMUT 510 used in these types of applications, the major axis (e.g., diameter) of the CMUT 510 will be multiple wavelengths wide (e.g., greater than 1 cm).

[0096] 3, an array of transducers including CMUT components and sensing transducers consistent with the inventive concept is shown. The US sensor 500 may include one or more ultrasonic transducer arrays, array elements 5010, such as the illustrated array elements 5010a and 5010b. Each of the array elements 5010a,b may include one or more CMUT components (e.g., at least 5, 10, or 20 CMUTs 510). In some embodiments, each of the array elements 5010a,b may include one or more sensors, sensors 5011 (e.g., at least 5, 10, or 20 sensors 5011). The sensors 5011 may include ultrasonic components (e.g., CMUT components) configured to acoustically couple to one or more CMUTs 510 of the array elements 5010a,b. In some embodiments, the array elements 5010a,b are configured to operate in a closed loop mode, for example where a signal generated by the sensor 5011 provides a feedback signal that is used by the sensor 500 (e.g., via the algorithm 115) to control a signal (e.g., a drive signal) provided to one or more CMUTs 510. In some embodiments, one or more ground guard lines (e.g., ground electrical traces) may be disposed between the CMUTs 510 and the sensor 5011 to reduce electrical crosstalk. In some embodiments, the device 100 includes at least 3, 6, or 8 array elements 5010.

[0097] 4A-5D, various cross-sectional views of a CMUT component configuration including a shaped plate consistent with the concepts of the present invention are shown. The CMUT 510 shown may include similar components to the CMUT 510 described with reference to FIG. 1 and elsewhere herein.

[0098] FIG. 4A illustrates a CMUT 510 that includes a CMUT configured to operate in a conventional mode (herein a "conventional mode CMUT") and includes a planar plate and a planar bottom electrode.

[0099] 4B illustrates a CMUT 510 that includes a conventional mode CMUT with a shaped plate that includes a stepped profile (e.g., includes one or more "profile steps"). The CMUT 510 of FIG. 4B includes a plate 512 that includes a stepped profile that includes step 5123, which includes two steps, i.e., ring-shaped steps 5123a and 5123b, as shown. S In some embodiments, one or more of the steps 5123 include a different shape, such as an oval, a rectangle, a triangle, and / or other shape (e.g., a shape similar to the shape of the cavity 513). In some embodiments, the CMUT 510 includes a plate 512 with three, four, or more steps. S Includes.

[0100] FIG. 4C shows a CMUT 510 that includes a conventional mode CMUT with a shaped plate that includes a graded profile (eg, a piecewise linear profile that includes one or more graded portions).

[0101] FIG. 4D shows a CMUT 510 that includes a conventional mode CMUT with a shaped plate that includes a curved profile.

[0102] FIG. 4E shows a CMUT 510 including a conventional mode CMUT with a shaped plate including a curved profile, where the edge of the plate contacts the edge of the bottom electrode (e.g., the edge of plate 512 contacts an insulating film 514 disposed on the bottom electrode 511).

[0103] A plate 512 including a molded profile, here plate 512 S CMUT 510, including shaped plate 512, as described herein, may provide advantages over "standard" CMUT components (e.g., current commercially available CMUT components including unshaped plates and electrodes, such as those shown in FIG. 4A). For example, shaped plate 512 Smay provide an enhanced electric field (e.g., at least a 2%, 5%, or 10% enhancement) and / or an increased electromechanical coupling efficiency (e.g., at least a 2%, 5%, 10%, 25%, and / or 50% increase). S may provide an improvement in both transmit and receive sensitivity, for example, at least a 50%, 75%, and / or 100% increase in sensitivity with a reduction in DC voltage (e.g., about a 39% reduction in DC voltage). S can allow for an increase in transient maximum output voltage, for example, at least a 1.1-fold increase (e.g., at least a 10% improvement) at 44% lower AC voltage. S allows for a reduction in drive voltage (e.g., at least a 2%, 5%, 10%, 25%, and / or 50% reduction in either or both of the bias voltage (DC) and excitation voltage (AC)), for example allowing for a 39% lower DC voltage and a 44% lower AC voltage (e.g., without degradation in performance of the CMUT510).

[0104] In some embodiments, the CMUT 510 includes one or more CMUT transducers configured for submerged applications and operates with one, two, or more of the following parameters: operating frequency between 10 KHz and 100 MHz, major axis (e.g., diameter) between 10 μm and 50 mm, plate thickness between 0.1 μm and 100 μm, and / or gap height between 10 nm and 5 mm.

[0105] In some embodiments, the shaped portion of the plate 512 includes a thickness that is 20% or less of the thickness of the plate 512 (e.g., the thickness of a central portion of the plate 512). Alternatively, or additionally, the shaped portion of the plate 512 may include a minimum thickness (e.g., a minimum thickness at the edges of the shaped portion) of at least 15% of the gap height or 5% of the effective gap height of the CMUT 510.

[0106] 5A illustrates a CMUT 510 that includes a CMUT configured to operate in a collapse mode (e.g., a "collapse mode CMUT") and includes a shaped plate that includes a stepped profile. The CMUT 510 of FIG. 5A includes a plate 512 with a stepped profile having a step 5123. S 5123, which includes two steps, ring-shaped steps 5123a and 5123b as shown. In some embodiments, one or more of the steps 5123 include different shapes, such as oval, rectangular, triangular, and / or other shapes (e.g., shapes similar to the shape of the cavity 513). In some embodiments, the CMUT 510 includes a plate 512 having three, four, or more steps. S Includes.

[0107] FIG. 5B shows a CMUT 510 that includes a collapse mode CMUT with a shaped plate that includes a sloped profile.

[0108] FIG. 5C shows a CMUT 510 that includes a collapse mode CMUT with a shaped plate that includes a curved profile.

[0109] FIG. 5D shows a CMUT 510, which includes a collapse mode CMUT with a shaped plate including a curved profile, where the edge of the plate contacts the edge of the bottom electrode (e.g., the edge of plate 512 contacts an insulating film 514 disposed on the bottom electrode 511).

[0110] Step plate 512 configured in collapse mode S The CMUT 510 including the shaped plate 512 may provide advantages over standard CMUT components configured in collapse mode (e.g., as shown in FIG. 4A). SThis configuration may provide an enhanced electric field (e.g., at least 2%, 5%, 10%, 25%, and / or 50% enhancement), may allow for improved transmit and receive sensitivity (e.g., at least 2%, 5%, or 10% improvement in either or both sensitivity), and may allow for reduced operating voltages (e.g., at least 2%, 5%, 10%, 25%, and / or 50% reduction in operating voltage).

[0111] 6A-6I, various charts and graphs of CMUT power output and other performance characteristics consistent with the inventive concepts are shown. Applicants have performed analyses of various shaped plate CMUT component configurations as described herein. The results of these analyses are shown in the figures and discussed below.

[0112] In the analysis conducted by the applicant, the CMUT 510 part is formed of a molded plate 512. S It has been shown that the CMUT 510 can include a shaped plate (e.g., plate 512 described herein) that can significantly improve the electric field and / or electromechanical coupling efficiency of the CMUT 510 (e.g., at least 2%, 5%, 10%, 25%, and / or 50% improvement in either or both), thereby improving either or both of the transmit and receive sensitivities (e.g., at least 2%, 5%, 10%, 25%, and / or 50% increase in either or both sensitivities, while maintaining a wide bandwidth, such as 50% to 150% bandwidth). S 512 and its fabrication method may be used for CMUTs operating in conventional (e.g., non-collapsed) mode, collapsed mode, or both. A standard CMUT includes plates and electrodes that are planar, which limits the electric field when the plates are biased with a DC voltage because the deflected plate 512 cannot move parallel to the bottom electrode 511. SAdvantages of having such a structure include, but are not limited to, a significant enhancement of the electric field (e.g., an increase of at least 2%, 5%, 10%, 25%, and / or 50%), an increase in electromechanical coupling efficiency (e.g., an increase of at least 2%, 5%, 10%, 25%, and / or 50%), a significant improvement in both transmit and receive sensitivity (e.g., an increase of at least 2%, 5%, or 10% in either or both), and / or a reduction in drive voltage (e.g., a reduction of at least 2%, 5%, 10%, 25%, and / or 50%).

[0113] A molded plate 512 for improving the electromechanical coupling efficiency to enhance both the transmission and reception sensitivity. S Various examples of CMUTs 510 including the shaped plate 512 are shown in FIGS. S The molded plate 512 includes a stepped portion 5123 that is a "multiple profile step" structure that can face downward relative to the planar substrate 511 (as shown and described with reference to Figures 4B, 5A, 8A, 10A, 22A, 24A, 26A, 28A, and elsewhere herein). S can be made of a conductive material so that a potential is applied to the shaped plate 512 S In some embodiments, the plate 512 may be applied to the stepped portion 5123 (e.g., the lower surface of the portion 5123). S In some embodiments, the material of the shaped plate 5122 may include an insulating material. In these embodiments, the stepped portion 5123 may include a conductive material, and an electrical potential may be applied to the underside of the stepped portion 5123. S The molded plate 512 includes a sloping portion 5124 that is a sloping structure, which can face downward relative to the planar substrate 511 (e.g., as shown and described with reference to Figures 4C, 5B, 8B, 10B, 22B, 24B, 26B, 28B, and elsewhere herein). SThe angled portion 5124 may include a thickness that is 50%, 60%, or 70% or less of the thickness of the cavity 513. The angled portion 5124 may include a thickness that is at least 2%, 5%, or 10% of the gap height of the cavity 513. The angled portion 5124 may include one, two, or more of a variety of similar and / or different materials, such as silicon. The angled portion 5124 may include a thickness that is at least 50%, 60%, or 70% of the thickness of the cavity 513. The angled portion 5124 may include one, two, or more of a variety of similar and / or different materials, such as silicon. S The molded plate 512 may comprise the same material as or a different material. S The plate 512 may be made of a conductive material, and the potential may be applied to the plate 512. S The pressure may be applied to the angled portion 5124 of the shaping plate 512 (e.g., the lower surface of the angled portion 5124). S In these embodiments, the angled portion 5124 may include a conductive material and an electrical potential may be applied to the underside of the angled portion 5124.

[0114] In some embodiments, the plate 512 includes one or more curved structures, curved portions 5125, which may be oriented downward relative to the planar substrate 511 (e.g., as shown and described with reference to Figures 4D-E, 5C-D, 8C-D, 10C-D, 22C-D, 24C-D, 26C-D, 28C-D). S The curved portion 5125 may include a thickness that is 50%, 60%, or 70% or less of the thickness of the cavity 513. The curved portion 5125 may include a thickness that is at least 2%, 5%, or 10% of the gap height of the cavity 513. The curved portion 5125 may include one, two, or more of a variety of similar and / or different materials, such as silicon. The curved portion 5125 may include a thickness that is at least 50%, 60%, or 70% of the thickness of the cavity 513. The curved portion 5125 may include a thickness that is at least 2%, 5%, or 10% of the gap height of the cavity 513. The curved portion 5125 may include one, two, or more of a variety of similar and / or different materials, such as silicon. S The molded plate 512 may comprise the same material as or a different material. S The molded plate 512 may be made of a conductive material so that an electrical potential is applied to the molded plate 512. SA potential may be applied to the curved portion 5125 (e.g., to the underside of the curved portion 5125) of the plate 512. In some embodiments, the plate 512 includes an insulating material. In these embodiments, the curved portion 5125 may include a conductive material such that a potential may be applied to the underside of the curved portion 5125. The profile of the curved portion 5125 may be derived from (e.g., set to resemble) the shape of a deflected flat plate driven with a large DC bias or a large AC excitation signal. This provides significant performance improvements (e.g., at least a 2%, 5%, 10%, 25%, and / or 50% increase in one or more performance parameters) without mechanically limiting the displacement of the center of the plate. The profile may approximate this shape, for example, with a horizontal step, reducing manufacturing complexity.

[0115] In some embodiments, the molded plate 512 S 4E, the curved portion 5125 is constructed and arranged to contact the substrate at an edge of the CMUT 510, e.g., at the contact region 5126. In these embodiments, the curvature of the curved portion 5125 may be constructed and arranged (e.g., optimized) to increase the drive voltage beyond the pull-in voltage, thereby improving the receiver sensitivity (e.g., at least a 2%, 5%, 10%, 25%, and / or 50% increase). For example, the contact region 5126 increases as more voltage is applied and the deflection of the plate 512 increases, reducing the lateral dimension of the plate 512 and making it stiffer to prevent collapse. This allows higher voltages to be applied to the CMUT 510 without reaching collapse.

[0116] Similar molded plate 512 SThese configurations may also be used in collapse mode CMUTs, for example as shown in Figures 5A-5D. Compared to conventional planar substrate configurations (e.g., as shown in Figure 4A), the most active areas associated with strong electric fields may be increased by up to 50%, 75%, and / or 100% using these configurations, thus resulting in significant enhancements in electromechanical coupling efficiency as described herein (e.g., at least 2%, 5%, 10%, 25%, and / or 50% efficiency increase). For example, Figures 5A-5D show a CMUT 510 in collapse mode having a configuration similar to the CMUT 510 of Figures 4B-4E, respectively.

[0117] Applicant has performed simulations (e.g., finite model analysis of various CMUT component configurations described herein). Figure 6A shows a simulation of deformation of a flat plate, where the plate is biased at a pull-in voltage of 90%. Figure 6B shows a simulation of deformation of a plate containing two "profile steps", where the plate is biased at a pull-in voltage of 90%. Figure 6C shows a simulation of deformation of a plate containing a sloped portion, where the plate is biased at a pull-in voltage of 90%. Figure 6D shows a simulation of deformation of a plate containing a curved portion, where the plate is biased at a pull-in voltage of 90%.

[0118] Applicant has evaluated various forming plate configurations (e.g., forming plate 512 described herein) when operating in a conventional mode. S The performance of the CMUT was designed and simulated, including a CMUT with a 7.5 MHz operating frequency, a 1.5 μm plate 512 thickness, a 21 μm plate 512 radius, and a 0.25 μm gap height (e.g., to obtain a suitable drive voltage, e.g., less than 200 V, less than 150 V, etc.). FIG. 6E shows the various shaped plate 512 configurations. SThe pull-in voltage from the configuration is shown in comparison to a standard CMUT component. As shown, in comparison, the pull-in voltage is reduced by up to 38.8%. Figures 6F and 6G show enhanced electric field and improved electromechanical coupling efficiency, respectively (e.g., at least 2%, 5%, 10%, 25%, and / or 50% increase in either or both). Figure 6H shows transmit (a) and receive (b) sensitivities biased at a pull-in voltage of 90%. Both transmit and receive sensitivities can be increased by at least 50% (e.g., about 93%) while operating at at least 10% lower DC bias (e.g., 38.8% lower DC bias). Maximum transient output voltages are similarly compared and are shown in Figure 6I. The shaped plate 512 S can generate over 1.1 times the sound pressure while being driven with 38.8% lower DC voltage and 43.8% lower AC voltage. S may also suppress higher harmonics.

[0119] 7A-10D, various cross-sectional views of piston-based CMUT components including shaped plates and / or shaped bottom electrodes consistent with the concepts of the present invention are shown. The illustrated CMUT 510 may include similar components to the CMUT 510 of FIG. 1 and / or described elsewhere herein. In some embodiments, the CMUT 510 of FIG. 7A-10D or described elsewhere herein may include a solid piston as described herein with reference to FIG. 47A-47B, or a non-solid piston as described herein with reference to FIG. 48A-48B.

[0120] FIG. 7A shows a CMUT 510 including a piston-based CMUT (e.g., a CMUT that includes a piston) configured to operate in a conventional mode (herein a “piston-based conventional mode CMUT”) and including a planar plate and a planar bottom electrode.

[0121] 7B shows a CMUT 510 comprising a piston-based conventional mode CMUT with a flat plate and a shaped bottom electrode with a stepped profile. The CMUT 510 of FIG. 7B includes a substrate 511 having a stepped profile including step 5113, which includes two steps, i.e., ring-shaped steps 5113a and 5113b, as shown. S In some embodiments, one or more of the steps 5113 include different shapes, such as ovals, rectangles, triangles, and / or other shapes (e.g., shapes similar to the shape of the cavity 513). In some embodiments, the CMUT 510 includes a substrate 511 with three, four, or more steps. S In some embodiments, the insulating film 514 covers the horizontal and / or vertical surfaces of one, two, or more stepped portions 5113, although only the horizontal surfaces are shown covered in FIG.

[0122] FIG. 7C shows a CMUT 510 that includes a piston-based conventional mode CMUT with a flat plate and a shaped bottom electrode that includes a sloped profile.

[0123] FIG. 7D shows a CMUT 510 that includes a piston-based conventional mode CMUT with a flat plate and a shaped bottom electrode that includes a curved profile.

[0124] FIG. 7E shows a CMUT 510 that includes a piston-based conventional mode CMUT with a planar plate and a shaped lower electrode that includes a curved profile in which the edge of the lower electrode contacts the edge of the plate (e.g., insulating film 514 contacts the edge of plate 512).

[0125] 8A shows a CMUT 510 including a piston-based conventional mode CMUT with a shaped plate including a stepped profile. The CMUT 510 of FIG. 8A includes a plate 512 having a stepped profile including step 5123, which includes two steps, i.e., ring-shaped steps 5123a and 5123b, as shown in the figure. SIn some embodiments, one or more of the steps 5123 include a different shape, such as an oval, a rectangle, a triangle, and / or other shape (e.g., a shape similar to the shape of the cavity 513). In some embodiments, the CMUT 510 includes a plate 512 with three, four, or more steps. S Includes.

[0126] FIG. 8B shows a CMUT 510 that includes a piston-based conventional mode CMUT with a shaped plate that includes a sloped profile.

[0127] FIG. 8C shows a CMUT 510 that includes a piston-based conventional mode CMUT with a shaped plate that includes a curved profile.

[0128] FIG. 8D shows a CMUT 510 that includes a piston-based conventional mode CMUT with a shaped plate that includes a curved profile in which an edge of the plate contacts an edge of the bottom electrode (e.g., an edge of plate 512 contacts an insulating film 514 disposed on bottom electrode 511).

[0129] Molded lower electrode 511 S and / or molded plate 512 SWhen operated in a conventional mode, a CMUT 510 including the piston (e.g., the piston-based CMUT described with reference to Figures 7B-8D) may provide advantages over a standard CMUT component (e.g., the standard CMUT including the piston shown in Figure 7A) when operated in a conventional mode, as described herein. For example, these advantages include, but are not limited to, wider operating bandwidth, higher transmit and / or receive sensitivity, harmonic suppression (e.g., enabling harmonic suppression), enhanced electric field (e.g., at least 2%, 5%, 10%, 25%, and / or 50% increase), improved electromechanical coupling efficiency (e.g., at least 2%, 5%, 10%, 25%, and / or 50% increase), increased transient maximum output voltage (e.g., at least 2%, 5%, 10%, 25%, and / or 50% increase), and / or reduced drive voltage (e.g., at least 2%, 5%, 10%, 25%, and / or 50% decrease for either or both of the bias voltage (DC) and excitation voltage (AC)).

[0130] In some embodiments, the piston 518 includes a thickness that is at least 50% of the thickness of the plate 512 and / or a thickness that is no greater than 5 times the thickness of the plate 512. In some embodiments, the piston 518 includes a diameter that is between 20% and 80% of the major axis (e.g., diameter) of the CMUT 510. In some embodiments, the shaped portions of the electrode 511 and / or plate 512 may include a minimum thickness (e.g., a minimum thickness at the edges of the shaped portions) of at least 15% of the gap height or 5% of the effective gap height of the CMUT 510.

[0131] FIG. 9A illustrates a CMUT 510 that includes a piston-based CMUT configured to operate in collapse mode (herein a "piston-based collapse mode CMUT") and includes a planar plate and a planar bottom electrode.

[0132] 9B shows a CMUT 510 comprising a piston-based collapse mode CMUT with a flat plate and a shaped bottom electrode with a stepped profile. The CMUT 510 of FIG. 9B includes a substrate 511 having a stepped profile including step 5113, which includes two steps, i.e., ring-shaped steps 5113a and 5113b, as shown. S In some embodiments, one or more of the steps 5113 include different shapes, such as ovals, rectangles, triangles, and / or other shapes (e.g., shapes similar to the shape of the cavity 513). In some embodiments, the CMUT 510 includes a substrate 511 with three, four, or more steps. S In some embodiments, the insulating film 514 covers the horizontal and / or vertical surfaces of one, two, or more stepped portions 5113, although only the horizontal surfaces are shown covered in FIG.

[0133] FIG. 9C shows a CMUT 510 that includes a piston-based collapse mode CMUT with a flat plate and a shaped bottom electrode that includes a sloped profile.

[0134] FIG. 9D shows a CMUT 510 that includes a piston-based collapse mode CMUT with a flat plate and a shaped bottom electrode that includes a curved profile.

[0135] FIG. 9E shows a CMUT 510 that includes a piston-based collapse mode CMUT with a planar plate and a shaped lower electrode that includes a curved profile in which the edge of the lower electrode contacts the edge of the plate (e.g., insulating film 514 contacts the edge of plate 512).

[0136] 10A shows a CMUT 510 including a piston-based collapse mode CMUT with a shaped plate including a stepped profile. The CMUT 510 of FIG. 10A includes a plate 512 having a stepped profile including step 5123, which includes two steps, i.e., ring-shaped steps 5123a and 5123b, as shown in the figure. SIn some embodiments, one or more of the steps 5123 include a different shape, such as an oval, a rectangle, a triangle, and / or other shape (e.g., a shape similar to the shape of the cavity 513). In some embodiments, the CMUT 510 includes a plate 512 with three, four, or more steps. S Includes.

[0137] FIG. 10B shows a CMUT 510 that includes a piston-based collapse mode CMUT with a shaped plate that includes a sloped profile.

[0138] FIG. 10C shows a CMUT 510 that includes a piston-based collapse mode CMUT with a shaped plate that includes a curved profile.

[0139] FIG. 10D shows a CMUT 510 including a piston-based collapse mode CMUT with a shaped plate including a curved profile in which the edge of the plate contacts the edge of the bottom electrode (e.g., the edge of plate 512 contacts an insulating film 514 disposed on the bottom electrode 511).

[0140] Molded lower electrode 511 S and / or molded plate 512 SWhen operated in collapse mode, a CMUT 510 including a piston (e.g., a piston-based CMUT as described with reference to Figures 9B-10D) may provide advantages over a standard CMUT component (e.g., a standard CMUT including a piston as shown in Figure 9A) when operated in collapse mode, as described herein. For example, these advantages include, but are not limited to, wider operating bandwidth, higher transmit and / or receive sensitivity, harmonic suppression (e.g., enabling harmonic suppression), enhanced electric field (e.g., at least a 2%, 5%, 10%, 25%, and / or 50% increase), improved electromechanical coupling efficiency (e.g., at least a 2%, 5%, 10%, 25%, and / or 50% increase), increased transient maximum output voltage (e.g., at least a 2%, 5%, 10%, 25%, and / or 50% increase), and / or reduced drive voltage (e.g., at least a 2%, 5%, 10%, 25%, and / or 50% decrease for either or both of the bias voltage (DC) and excitation voltage (AC)).

[0141] 11A-20, various charts and graphs of CMUT power output and other performance characteristics consistent with the inventive concepts are shown. Applicants have performed analyses of the various shaped plate CMUT component configurations described herein. The results of these analyses are shown in the figures and discussed below.

[0142] Applicant's analysis indicates that a CMUT component of the inventive concept may be constructed from a piston (e.g., a piston attached to a plate 512, referred to herein as a "piston plate") and a shaped electrode (e.g., a shaped lower electrode 511). S and / or molded plate 512 S) which have been shown to significantly improve either or both of the transmit and receive sensitivities (e.g., at least 2%, 5%, 10%, 25%, and / or 50% increase in either or both sensitivities) and significantly increase the output acoustic pressure (e.g., at least 2%, 5%, 10%, 25%, and / or 50% increase while maintaining a wide bandwidth at a lower drive voltage). The piston-based CMUT component configuration of the inventive concept and its fabrication method may be used for CMUTs operating in either or both of conventional and collapsed modes. Standard flat plate and flat electrode piston-based CMUT configurations limit the electromechanical transformation ratio due to the inability of the deflected plate to move parallel to the lower flat electrode when the plate is biased with a DC voltage. The piston and shaped electrode (e.g., lower electrode 511) S and / or Plate 512 S Advantages of having such a gyro-coupled oscillator include, but are not limited to, significantly improved transmit and receive sensitivity (e.g., transmit and / or receive sensitivity increased by at least 2%, 5%, 10%, 25%, and / or 50%), wider operating bandwidth (e.g., bandwidth increased by at least 2%, 5%, 10%, 25%, and / or 50%), harmonic suppression (e.g., harmonics can be suppressed by at least 2%, 5%, 10%, 25%, and / or 50%), lower drive voltage (e.g., reduced by at least 2%, 5%, 10%, 25%, and / or 50%), and / or improved electromechanical transformation ratio (e.g., increased by at least 2%, 5%, 10%, 25%, and / or 50%).

[0143] Various examples of CMUTs 510 including piston and shaped electrodes (e.g., bottom electrode 511 and / or plate 512) for improving both transmit and receive sensitivity are shown in Figures 7B-10D. A piston-based CMUT may include a piston plate including a mass piston 518 disposed on a plate 512, as shown for example in Figure 7A. In some embodiments, the bottom electrode 511 includes a stepped portion 5113 that is a multiple profile step structure. S1, 7B, 9B, 21B, 23B, 25B, 27B, and elsewhere herein. Alternatively or additionally, a shaped bottom electrode 511 S 5C, 6C, 7C, 9C, 21C, 23C, 25C, 27C, and elsewhere herein. The angled portion 5114 may include one, two, or more similar and / or different materials, such as silicon. In some embodiments, the angled portion 5114 includes a material similar to the substrate 511. The angled portion 5114 may include a maximum thickness where the angled portion 5114 is close to, but does not fully contact, the plate 512 at maximum deflection. The angled portion 5114 may include a width of at least 10%, or 20%, of the length of the major axis of the cavity 513. The angled portion 5114 may include a maximum height of at least 30%, 20%, or 10% of the gap height of the cavity 513. In some embodiments, the shaped bottom electrode 511 may include a width of at least 10%, 20%, or 10%, of the gap height of the cavity 513. In some embodiments, the shaped bottom electrode 511 may include a width of at least 10%, 20%, or 10%, of the length of the major axis of the cavity 513. S 5 includes a curved portion 5115 that is a curved structure, as shown and described with reference to Figures 1, 7D-7E, 9D-9E, 21D-21E, 25D-25E, 27D-27E, and elsewhere herein. The profile of the curved portion 5115 may be derived from (e.g., set to resemble) the shape of a deflected flat plate driven with a large DC bias or a large AC excitation signal. The curved portion 5115 may include a curvature that approximates the curvature of the deflection profile of the plate 512. The curved portion 5115 may include a height that is at least 2%, 5%, or 10% of the gap height of the cavity 513.

[0144] In some embodiments, the lower electrode 511 (e.g., electrode 511 S) is constructed and arranged to contact the plate 512 at an edge of the CMUT 510, e.g., at a contact region 5116, as shown in Figures 7E, 9E, 21E, 23E, and 25E. The area associated with the contact region 5116 depends on the magnitude of the voltage applied to the CMUT 510. The curvature of the curved portion 5115 can be constructed and arranged (e.g., optimized) to improve the receiver sensitivity by increasing the drive voltage beyond the pull-in voltage (e.g., increasing the sensitivity by at least 2%, 5%, 10%, 25%, and / or 50%). For example, during deflection of the plate 512, the plate 512 gradually comes into contact with the curved portion 5115, causing the deflectable portion of the plate 512 to gradually contract, increasing the spring constant of the plate 512 and increasing the pull-in voltage.

[0145] In some embodiments, the CMUT 510 includes a shaped plate 512 S The CMUT 510 includes a piston-based CMUT having a shaped plate 512 including a stepped portion 5123, as shown in FIG. S In some embodiments, the CMUT 510 may include a shaped plate 512 that includes an angled portion 5124, as shown in FIG. S In some embodiments, the CMUT 510 includes a shaped plate 512 that includes a curved portion 5125, as shown in FIG. S The profile of the curved portion 5125 may be derived from (e.g., set to resemble) the shape of a deflected flat plate driven with a large DC bias or a large AC excitation signal. In some embodiments, the shaped plate 512 including the curved portion 5125 may be Scan contact the bottom electrode 511 at a contact region 5126, which is shown in Figures 4E, 5D, 8D, 10D, 22D, 24D, 26D, 27E, and 28D. The curvature of the curved portion 5125 can be constructed and arranged (e.g., optimized) to increase the drive voltage beyond the pull-in voltage, thereby improving the receiver sensitivity (e.g., increasing the sensitivity by at least 2%, 5%, 10%, 25%, and / or 50%), as described herein. The area associated with the contact region 5126 depends on the magnitude of the voltage applied to the CMUT 510.

[0146] A CMUT 510 configuration of the inventive concept including a piston and shaped electrodes can be operated in collapse mode, for example as shown in Figures 9A-10D, which show a CMUT 510 in collapse mode having a configuration similar to Figures 7B-8D, respectively.

[0147] In some embodiments, the shaped electrode 511 S comprises a conductive material. Piston 518 (e.g., a piston attached to plate 512) may comprise either a conductive material or an insulating material. Compared to conventional planar plate and planar electrode component configurations (e.g., as shown in FIG. 7A), the most active areas having the strongest electric fields may be increased by up to 50%, 75%, and / or 100% using the configurations shown in FIGS. 7B-10D, resulting in significant increases in electromechanical coupling efficiency (e.g., at least 2%, 5%, 10%, 25%, and / or 50% increase) as described herein.

[0148] Applicant has designed and simulated the performance of piston-based CMUTs with various shaped electrode configurations operating in conventional mode. The following parameters were used in the simulation: operating frequency 7.5 MHz, plate 512 thickness 1.5 μm, plate 512 radius 21 μm, and gap height 0.25 μm (e.g., to obtain a suitable drive voltage, e.g., less than 200 V peak-to-peak). The piston width was set (e.g., optimized) to half the plate radius to obtain the best sensitivity without sacrificing bandwidth. In some embodiments, the piston 518 includes one or more dimensions described with reference to FIG. 1 and / or elsewhere herein. The resonant frequency increases to 10 MHz with an increase in the piston plate spring constant, and the pull-in voltage may increase by about 22% (e.g., at least a 5% and / or 10% increase). FIGS. 11A-11D show the transmit and receive sensitivities of various CMUT component configurations biased at a pull-in voltage of 90%. FIG. 11A compares the transmit sensitivity of simulated CMUTs with various bottom electrodes 511. FIG. 11B compares the transmit sensitivity of simulated CMUTs with various plates 512. FIG. 11C compares the receive sensitivity of simulated CMUTs with various bottom electrodes 511. FIG. 11D compares the receive sensitivity of simulated CMUTs with various plates 512. Both the transmit and receive sensitivity can be increased by at least 50%, 75%, 100%, 125%, and / or 150% (e.g., as described below). A comparison of maximum transient output voltages for CMUT component configurations using various electrodes 511(a) and various plates 512(b) is shown in FIG. 12. In the simulation, a shaped plate 512 was used. S and Molded Electrode 511 SIt has been shown that the component configuration can generate 2.2 times more acoustic pressure while being driven by the same drive voltage. FIG. 13 shows a comparison of electromechanical transformation ratio and DC bias voltage for various component configurations described herein. The DC bias voltage is set to 90% of the pull-in voltage. A conventional planar CMUT design without a piston has the lowest electromechanical transformation ratio and DC bias. By adding a piston, the plate is significantly strengthened and the pull-in voltage is increased the most. However, adding a shaped electrode significantly improves the electromechanical transformation ratio (e.g., at least 2%, 5%, 10%, 25%, and / or 50% improvement) while significantly lowering the DC. The curved electrode configuration has the best transformation ratio at the lowest DC bias, followed by the tilted electrode, and then the two-step electrode. The shaped plate configuration has a higher DC due to the plate being stiffer than the sub-electrode.

[0149] FIG. 14A shows a simulation of deformation of a flat plate of a collapse mode CMUT, where the plate is biased with a pull-in voltage of 100%. FIG. 14B shows a close-up of the simulation of FIG. 14A. FIG. 15A shows a simulation of deformation of a flat piston plate of a collapse mode CMUT, where the plate is biased with a pull-in voltage of 100%. FIG. 15B shows a close-up of the simulation of FIG. 15A. FIG. 16A shows a simulation of deformation of a flat piston plate of a collapse mode CMUT including an electrode 511 with a sloped profile. FIG. 16B shows a close-up of the simulation of FIG. 16A.

[0150] 17A and 17B show graphs comparing the transmit and receive sensitivities of the conventional CMUT of FIG. 14A, the piston-based CMUT of FIG. 15A, and the piston-based CMUT of FIG. 16A including an electrode 511 with a graded profile, respectively.

[0151] 18A-18C show simulations of the CMUTs of FIGS. 14A, 15A, and 16A, respectively, showing the maximum vibration position for each design relative to the equilibrium position.

[0152] FIG. 19 shows a graph comparing the transient acoustic output pressure of the CMUTs of FIG. 14A, FIG. 15A, and FIG. 16A. FIG. 20 shows a table showing the percentage increase and decrease of the key characteristics of these CMUT designs. As shown, the resonant frequency of the piston-based CMUT of FIG. 15A is lower than that of the CMUT of FIG. 14A, but the transmit and receive sensitivities, as well as the maximum transient output pressure, are all increased. The piston-based CMUT of FIG. 16A, which includes an electrode 511 having a graded profile, shows further improvement in these metrics and a reduction in pull-in voltage (e.g., at least 2%, 5%, 10%, 25%, and / or 50% reduction in pull-in voltage). The transmit and receive sensitivities of the CMUT 510 configurations of FIG. 14A, FIG. 15A, and FIG. 16A are improved by more than 35% at about 50% excitation voltage, as shown.

[0153] 21A-28D, various cross-sectional views of CMUT components configured for airborne applications and including shaped plates and / or shaped bottom electrodes are shown consistent with the concepts of the present invention. The CMUT 510 shown may include similar components to the CMUT 510 described with reference to FIG. 1 and elsewhere herein, such as components 511, 512, 513, 514, 515, 516, and 517 shown in the figures.

[0154] 21B to 21E show the ventilation hole 516 and the molded substrate 511. S 22A-22D show a CMUT 510 including a vent hole 516 and a molded plate 512. S 23B-23E show a CMUT 510 including trenches 517 (e.g., four ring-shaped fluid channels that penetrate dielectric film 514 in substrate 511 as shown) and a molded substrate 511. S 24A-24D show a CMUT 510 including trenches 517 (e.g., four ring-shaped fluid channels disposed in a substrate 511 and penetrating a dielectric film 514, as shown) and a shaped plate 512. S 25B-25E show a CMUT 510 including a vent 516, a piston 518, and a molded substrate 511. S26A-26D show a CMUT 510 including a vent 516, a piston 518, and a molded plate 512. S 27B-27E show a CMUT 510 including vent holes 516, trenches 517 (e.g., four ring-shaped fluid channels shown disposed in the substrate 511 and extending through the dielectric film 514 as shown), and a molded substrate 511. S 28A-28D show a CMUT 510 including a vent hole 516, a trench 517 (e.g., four ring-shaped fluid channels disposed in a substrate 511 and penetrating a dielectric film 514, as shown), and a shaped plate 512. S 1 shows a CMUT 510 including:

[0155] FIG. 21A shows a CMUT 510 that includes an air-compatible conventional mode CMUT that includes a "vent through via" (eg, a hole through bottom electrode 511 as shown), a planar plate, and a planar bottom electrode.

[0156] 21B illustrates a CMUT 510 that includes an air-compatible conventional mode CMUT that includes a vent through via, a planar plate, and a shaped bottom electrode that includes a stepped profile (e.g., includes one or more "profile steps"). The CMUT 510 of FIG. 21B includes a substrate 511 having a stepped profile that includes step 5113, which includes two steps, i.e., ring-shaped steps 5113a and 5113b, as shown. S In some embodiments, one or more of the steps 5113 include different shapes, such as ovals, rectangles, triangles, and / or other shapes (e.g., shapes similar to the shape of the cavity 513). In some embodiments, the CMUT 510 includes a substrate 511 with three, four, or more steps. S In some embodiments, the insulating film 514 covers the horizontal and / or vertical surfaces of one, two, or more stepped portions 5113, although only the horizontal surfaces are shown covered in FIG.

[0157] FIG. 21C shows a CMUT 510 that includes an air-compatible conventional mode CMUT that includes a vented through via, a flat plate, and a shaped bottom electrode that includes a sloped profile.

[0158] FIG. 21D shows a CMUT 510 that includes an air-compatible conventional mode CMUT that includes a vent through via, a flat plate, and a shaped bottom electrode that includes a curved profile.

[0159] FIG. 21E shows a CMUT 510 including an air-compatible conventional mode CMUT including a vent through via, a planar plate, and a shaped bottom electrode with a curved profile where the edge of the bottom electrode contacts the edge of the plate (e.g., insulating film 514 contacts the edge of plate 512).

[0160] FIG. 22A shows a CMUT 510 including an air-compatible conventional mode CMUT including a vent through via and a molded plate with a stepped profile. The CMUT 510 of FIG. 22A includes a plate 512 having a stepped profile including step 5123, which includes two steps, i.e., ring-shaped steps 5123a and 5123b, as shown in the figure. S In some embodiments, one or more of the steps 5123 include a different shape, such as an oval, a rectangle, a triangle, and / or other shape (e.g., a shape similar to the shape of the cavity 513). In some embodiments, the CMUT 510 includes a plate 512 with three, four, or more steps. S Includes.

[0161] FIG. 22B shows a CMUT 510 that includes an air-compatible conventional mode CMUT that includes vent through vias and a shaped plate that includes a sloped profile.

[0162] FIG. 22C shows a CMUT 510 that includes an air-compatible conventional mode CMUT that includes vent through vias and a shaped plate that includes a curved profile.

[0163] FIG. 22D shows a CMUT 510 including an air-compatible conventional mode CMUT including a vent through via and a shaped plate including a curved profile where an edge of the plate contacts an edge of the bottom electrode (e.g., an edge of plate 512 contacts an insulating film 514 disposed on bottom electrode 511).

[0164] FIG. 23A illustrates a CMUT 510 that includes an air-compatible conventional mode CMUT that includes vent through vias, fluidic channels, a planar plate, and a planar bottom electrode consistent with the concepts of the present invention.

[0165] 23B shows a CMUT 510 including an air-compatible conventional mode CMUT including vent through vias, fluidic channels, a planar plate, and a shaped bottom electrode with a stepped profile. The CMUT 510 of FIG. 23B is a substrate 511 having a stepped profile including step 5113, which includes two steps, i.e., ring-shaped steps 5113a and 5113b, as shown. S In some embodiments, one or more of the steps 5113 include different shapes, such as ovals, rectangles, triangles, and / or other shapes (e.g., shapes similar to the shape of the cavity 513). In some embodiments, the CMUT 510 includes a substrate 511 with three, four, or more steps. S In some embodiments, the insulating film 514 covers the horizontal and / or vertical surfaces of one, two, or more stepped portions 5113, although only the horizontal surfaces are shown covered in FIG.

[0166] FIG. 23C shows a CMUT 510 that includes an air-compatible conventional mode CMUT that includes vent through vias, fluidic channels, a planar plate, and a shaped bottom electrode with a sloped profile.

[0167] FIG. 23D shows a CMUT 510 that includes an air-compatible conventional mode CMUT that includes vent through vias, fluidic channels, a planar plate, and a shaped bottom electrode with a curved profile.

[0168] FIG. 23E shows a CMUT 510 that includes an air-compatible conventional mode CMUT that includes a vent through via, a fluidic channel, a planar plate, and a shaped bottom electrode with a curved profile where the edge of the bottom electrode contacts the edge of the plate (e.g., insulating film 514 contacts the edge of plate 512).

[0169] 24A shows a CMUT 510 including an air-compatible conventional mode CMUT including vent through vias, fluid channels, and a molded plate with a stepped profile. The CMUT 510 of FIG. 24A includes a plate 512 having a stepped profile including step 5123, which includes two steps, i.e., ring-shaped steps 5123a and 5123b, as shown. S In some embodiments, one or more of the steps 5123 include a different shape, such as an oval, a rectangle, a triangle, and / or other shape (e.g., a shape similar to the shape of the cavity 513). In some embodiments, the CMUT 510 includes a plate 512 with three, four, or more steps. S Includes.

[0170] FIG. 24B shows a CMUT 510 that includes an air-compatible conventional mode CMUT that includes vent through vias, fluidic channels, and a shaped plate with a sloped profile.

[0171] FIG. 24C shows a CMUT 510 that includes an air-compatible conventional mode CMUT that includes vent through vias, fluidic channels, and a shaped plate with a curved profile.

[0172] FIG. 24D shows a CMUT 510 that includes an air-compatible conventional mode CMUT that includes a vent through via, a fluid channel, and a shaped plate having a curved profile in which an edge of the plate contacts an edge of the bottom electrode (e.g., an edge of plate 512 contacts an insulating film 514 disposed on bottom electrode 511).

[0173] FIG. 25A shows a CMUT 510 that includes an air-compatible piston-based conventional mode CMUT that includes a vented through-via, a planar plate, and a planar bottom electrode.

[0174] FIG. 25B shows a CMUT 510 including an air-compatible piston-based conventional mode CMUT including a vented through via, a flat plate, and a shaped bottom electrode with a stepped profile. The CMUT 510 of FIG. 25B is a substrate 511 having a stepped profile including step 5113, which includes two steps, i.e., ring-shaped steps 5113a and 5113b, as shown. S In some embodiments, one or more of the steps 5113 include different shapes, such as ovals, rectangles, triangles, and / or other shapes (e.g., shapes similar to the shape of the cavity 513). In some embodiments, the CMUT 510 includes a substrate 511 with three, four, or more steps. S In some embodiments, the insulating film 514 covers the horizontal and / or vertical surfaces of one, two, or more stepped portions 5113, although only the horizontal surfaces are shown covered in FIG.

[0175] FIG. 25C shows a CMUT 510 that includes an air-compatible piston-based conventional mode CMUT that includes a vented through-via, a planar plate, and a shaped bottom electrode with a sloped profile.

[0176] FIG. 25D shows a CMUT 510 that includes an air-compatible piston-based conventional mode CMUT that includes a vented through-via, a flat plate, and a shaped bottom electrode with a curved profile.

[0177] FIG. 25E shows a CMUT 510 that includes an air-compatible piston-based conventional mode CMUT that includes a vent through via, a planar plate, and a shaped bottom electrode with a curved profile where the edge of the bottom electrode contacts the edge of the plate (e.g., insulating film 514 contacts the edge of plate 512).

[0178] 26A shows a CMUT 510 including an air-compatible piston-based conventional mode CMUT including a vented through via and a molded plate with a stepped profile. The CMUT 510 of FIG. 26A includes a plate 512 having a stepped profile including step 5123, which includes two steps, i.e., ring-shaped steps 5123a and 5123b, as shown in the figure. S In some embodiments, one or more of the steps 5123 include a different shape, such as an oval, a rectangle, a triangle, and / or other shape (e.g., a shape similar to the shape of the cavity 513). In some embodiments, the CMUT 510 includes a plate 512 with three, four, or more steps. S Includes.

[0179] FIG. 26B shows a CMUT 510 that includes an air-compatible piston-based conventional mode CMUT that includes vent through vias and a molded plate with a sloped profile.

[0180] FIG. 26C shows a CMUT 510 that includes an air-compatible piston-based conventional mode CMUT that includes vent through vias and a molded plate with a curved profile.

[0181] FIG. 26D shows a CMUT 510 including an air-compatible piston-based conventional mode CMUT including a vent through via and a shaped plate having a curved profile where the edge of the plate contacts the edge of the bottom electrode (e.g., the edge of plate 512 contacts the insulating film 514 disposed on the bottom electrode 511).

[0182] FIG. 27A illustrates a CMUT 510 that includes an air-compatible piston-based conventional mode CMUT that includes vent through vias, fluidic channels, a planar plate, and a planar bottom electrode consistent with the concepts of the present invention.

[0183] 27B shows a CMUT 510 including an air-compatible piston-based conventional mode CMUT including vent through vias, fluidic channels, a planar plate, and a shaped bottom electrode with a stepped profile. The CMUT 510 of FIG. 27B is formed on a substrate 511 having a stepped profile including step 5113, which includes two steps, i.e., ring-shaped steps 5113a and 5113b, as shown. S In some embodiments, one or more of the steps 5113 include different shapes, such as ovals, rectangles, triangles, and / or other shapes (e.g., shapes similar to the shape of the cavity 513). In some embodiments, the CMUT 510 includes a substrate 511 with three, four, or more steps. S In some embodiments, the insulating film 514 covers the horizontal and / or vertical surfaces of one, two, or more stepped portions 5113, although only the horizontal surfaces are shown covered in FIG.

[0184] FIG. 27C shows a CMUT 510 that includes an air-compatible piston-based conventional mode CMUT that includes vent through vias, fluidic channels, a planar plate, and a shaped bottom electrode with a sloped profile.

[0185] FIG. 27D shows a CMUT 510 that includes an air-compatible piston-based conventional mode CMUT that includes vent through vias, fluidic channels, a planar plate, and a shaped bottom electrode with a curved profile.

[0186] FIG. 27E shows a CMUT 510 that includes an air-compatible piston-based conventional mode CMUT that includes a vent through-via, a fluidic channel, a planar plate, and a shaped bottom electrode with a curved profile where the edge of the bottom electrode contacts the edge of the plate (e.g., insulating film 514 contacts the edge of plate 512).

[0187] 28A shows a CMUT 510 including an air-compatible piston-based conventional mode CMUT including a vented through via, fluidic channels, and a molded plate with a stepped profile. The CMUT 510 of FIG. 28A includes a plate 512 having a stepped profile including step 5123, which includes two steps, i.e., ring-shaped steps 5123a and 5123b, as shown. S In some embodiments, one or more of the steps 5123 include a different shape, such as an oval, a rectangle, a triangle, and / or other shape (e.g., a shape similar to the shape of the cavity 513). In some embodiments, the CMUT 510 includes a plate 512 with three, four, or more steps. S Includes.

[0188] FIG. 28B shows a CMUT 510 that includes an air-compatible piston-based conventional mode CMUT that includes vent through vias, fluidic channels, and a molded plate with a sloped profile.

[0189] FIG. 28C shows a CMUT 510 that includes an air-compatible piston-based conventional mode CMUT that includes vent through vias, fluid channels, and a shaped plate with a curved profile.

[0190] FIG. 28D shows a CMUT 510 that includes an air-compatible piston-based conventional mode CMUT that includes a vent through-via, a fluid channel, and a shaped plate having a curved profile in which the edge of the plate contacts the edge of the bottom electrode (e.g., the edge of plate 512 contacts an insulating film 514 disposed on the bottom electrode 511).

[0191] The bandwidth of a vacuum-based CMUT (e.g., a vacuum-based CMUT as shown in FIG. 4A ) is limited by resistance from the air medium when operating in air (e.g., when used in airborne applications). In some embodiments, to increase the operating bandwidth, squeeze film damping is introduced by venting the vacuum cavity. In some embodiments, a trench 517, including one or more fluid trenches or other paths, can be included to significantly increase the bandwidth while simultaneously increasing sensitivity and reducing the drive voltage. In some embodiments, a trench 517 is included in combination with a shaped electrode (e.g., electrodes 511 and / or 512), which further increases the sensitivity (e.g., at least 2%, 5%, 10%, 25%, and / or 50% increase in sensitivity) and further reduces the drive voltage (e.g., at least 2%, 5%, 10%, 25%, and / or 50% voltage reduction). A shaped electrode (e.g., shaped electrode 511 S and / or molded plate 512 S Advantages of having both a piston-based CMUT (e.g., including one or more pistons 518) and a trench 517 include, but are not limited to, a wide operating bandwidth, such as between 2%-200%, easy control of the bandwidth by adjusting the height of the trench 517, very low drive voltage, e.g., as low as 50V, such as a maximum of 10V or 5V, high transmit and receive sensitivity, and / or simplified packaging and housing (e.g., by use of a PCB). Additionally, advantages of having a piston-based CMUT (e.g., including one or more pistons 518) also include an increase in output acoustic pressure (e.g., an increase of at least 2%, 5%, 10%, 25%, and / or 50%).

[0192] 29A-29D, top views of a portion of a CMUT component including various patterns of fluidic trenches consistent with the concepts of the present invention are shown. In FIG. 29A, the CMUT 510 includes trench 517 with a ring-shaped fluidic trench as shown. In FIG. 29B, the CMUT 510 includes trench 517a with a trench arranged to surround an array of micropillars, i.e., micropillars 5171, as shown. Micropillars 5171 may include a major axis (e.g., diameter) that is 5%, 10%, or 20% or less of the major axis (e.g., diameter) of cavity 513. In FIG. 29C, the CMUT 510 includes trench 517b with a trench arranged in a fan-shaped pattern as shown. In FIG. 29D, the CMUT 510 includes trench 517b, which includes a hybrid set of trenches, each including trench 517a surrounding an array of micropillars 5171 located near the center of the CMUT 510, and fan-shaped trenches 517b located at the periphery of the CMUT 510, as shown. A gas squeeze film is introduced when the cavity is vented by a through via (e.g., vent hole 516 as described herein) and is controlled by the fluid trenches. The fluid trenches of trench 517 control the bandwidth by adjusting the stiffening and damping effects of the squeeze film, where the stiffening effect acts as a spring and the damping effect represents a damper. The illustrated patterns and / or combinations of these patterns can effectively adjust the stiffening and damping effects of the squeeze film while simultaneously lowering the pull-in voltage by increasing the area of ​​the electrodes on the substrate. Because the displacement of the plate 512 varies from zero at its edges to a maximum at its center, different regions of the plate 512 contribute differently to the output pressure and damping of the CMUT 510. The micro-pillars 5171 may include smaller pillars near the center of the CMUT 510, and the relative trench area may be larger near this center (e.g., if the displacement of the plate 512 is large, more trench area is needed to counter the stiffening effect of the squeeze film).The micro-pillars 5171 can be larger near the edges of the CMUT 510 where the displacement of the plate 512 is smaller, thus requiring less trench area and allowing more area to be allocated to the electrodes on the micro-pillars 5171.

[0193] 30A-30Y, various charts and graphs of CMUT power output and other performance characteristics consistent with the inventive concepts are shown. Applicants have performed analyses of various airborne CMUT component configurations described herein. The results of these analyses are shown in the figures and discussed below.

[0194] Analysis performed by applicants indicates that airborne CMUT component configurations may include shaped electrodes and / or fluidic trenches to significantly broaden the operating bandwidth of airborne CMUTs and lower the drive voltage while improving transmit and receive sensitivity, as discussed above. The bandwidth of vacuum-based CMUTs is limited by the small resistance from the air medium. In some embodiments, a CMUT (e.g., CMUT 510 described herein) includes a squeeze film damper and a fluidic trench (e.g., trench 517) configured to enable a tradeoff between sensitivity and bandwidth by design. Advantages of having shaped electrodes and fluidic trenches are described herein.

[0195] Various examples of airborne CMUTs 510 with shaped electrodes and / or fluid trenches to improve both transmit and receive sensitivity are shown in Figures 21A-28D. In some embodiments, the CMUT 510 includes an air vent 516 that includes one or more vias, such as one or more vias that pass through the bottom electrode 511 between the cavity 513 and the medium surrounding the CMUT 510. In some embodiments, the vias may be located near the center of the CMUT 510 and / or the one or more vias may be located proximate an edge of the CMUT 510. The location and distribution of the one or more vias may be configured to optimize performance.

[0196] The air-compatible CMUT may include vent holes 516 through a planar bottom electrode 511, as shown, for example, in FIG. 21A. In some embodiments, the bottom electrode 511 may be an electrode 511 including multiple profile step structures (e.g., two profile step structures), as shown, for example, in FIG. 21B. S 21C, the shaped bottom electrode 511 includes a stepped portion 5113 and a vent hole 516. In some embodiments, as shown in FIG. S The shaped bottom electrode 511 includes an inclined portion 5114 and a vent hole 516. S 21D, may include curved portions 5115 and vent holes 516. The profile of curved portions 5115 may be derived from (e.g., set similar to) the deflected shape of a flat plate driven with a large DC bias or a large AC excitation signal.

[0197] In some embodiments, a shaped bottom electrode 511 including a curved portion 5115 and vent holes 516. S21E, the plate 512 is in contact with an edge of the CMUT 510, e.g., at a contact region 5116. The curvature of the curved portion 5115 may be constructed and arranged (e.g., optimized) to improve the receiver sensitivity by increasing the drive voltage over the pull-in voltage (e.g., at least 2%, 5%, 10%, 25%, and / or 50% increase). For example, during deflection of the plate 512, the plate 512 gradually comes into contact with the curved portion 5115, causing the plate 512 to gradually contract, increasing the spring constant of the plate 512 and increasing the pull-in voltage. In some embodiments, the plate 512 includes a stepped portion 5123 and the bottom electrode 511 includes a vent hole 516, as shown in FIG. 22A. The plate 512 may include a slanted portion 5124 and the bottom electrode 511 includes a vent hole 516, as shown in FIG. 22B. In some embodiments, the plate 512 includes a curved portion 5125 and the bottom electrode 511 includes a vent hole 516, as shown in FIG. 22C. The profile of the curved portion 5125 may be derived from (e.g., set to resemble) the shape of a deflected flat plate driven with a large DC bias or a large AC excitation signal. In some embodiments, the plate 512 with the curved portion 5125 may be contacted with an insulating film 514 on the bottom electrode 511 at a contact region 5126, as shown in FIG. 22D, and the curvature of the curved portion 5125 may be constructed and arranged (e.g., optimized) to improve the receive sensitivity (e.g., at least 2%, 5%, 10%, 25%, and / or 50% increase in sensitivity) by increasing the drive voltage above the pull-in voltage, as described herein. In some embodiments, the bottom electrode 511 may include a trench 517 (e.g., made by an etching process), and the trench of the trench 517 may be configured to tune the squeeze film damper. CMUT 510 configurations including trenches 517 are shown in Figures 23A-24D. The configurations shown in Figures 23A-24D may be similar to the configurations shown in Figures 21A-22D, respectively, and may include similar shaped electrodes, as described herein. CMUT 510 including piston-based CMUTs, each including a piston 518, are shown in Figures 25A-28D.The configurations shown in Figures 25A-28D may be similar to the configurations shown in Figures 21A-24D, respectively, and may include similar shaped electrodes, vent holes, and / or fluidic trenches, as described herein.

[0198] Applicants have designed and simulated the performance of airborne CMUTs including various configurations as described herein. In the simulations, the following parameters were used: operating frequency of 100 kHz, plate 512 thickness of 50 μm, plate 512 radius of 1500 μm, and gap height as small as 1 μm. In the simulations, a shaped electrode (shaped electrode 511 S and / or molded plate 512 S It has been shown that the pull-in voltage is reduced by about 70% when a gap height of 100 μm or less is used. With the inclusion of the trench 517, the pull-in voltage remains low. The pressure exerted by the squeeze film damper on the substrate is reduced by a factor of 50, so that the squeeze film damper dominates the dynamic behavior of the CMUT 510. However, the bandwidth may be broadened by at least 30% based on the height of the trench 517 of the associated CMUT 510. The transmit and / or receive sensitivity is also improved (e.g., at least 2%, 5%, 10%, 25%, and / or 50% sensitivity increase in either or both) by placing the gap height in the sub-micrometer range (e.g., less than 1 μm). Simulations have also shown that the bandwidth may be easily broadened by up to 30% based on the height of the trench 517 of the associated CMUT 510, e.g., a trench height greater than 1 μm and / or less than 100 μm. In configurations with lower gap heights, the bandwidth may exceed 150%. Simulations performed by applicants have shown that various CMUT 510 configurations described herein can enable drive voltages down to 10V, which is impractical to achieve in standard configurations. For example, the pull-in voltage of the CMUT in a planar configuration was measured at 32.8V, while a stepped profile geometry achieved a 40% reduction in pull-in voltage (19.7V), a tilted geometry achieved a 59% reduction in pull-in voltage (13.4V), and a curved geometry achieved a 67% reduction in pull-in voltage (10.8V).

[0199] FIG. 30A shows the shape of a deflected planar plate biased at a pull-in voltage of 90%.

[0200] FIG. 30B shows the squeeze film pressure on the substrate for a standard planar electrode, vented CMUT without a fluidic trench.

[0201] FIG. 30C shows a front view of trench 517 including a fluidic trench for a CMUT 510 including a standard planar electrode CMUT.

[0202] FIG. 30D shows a cross-sectional view of a fluidic trench for a standard planar electrode CMUT.

[0203] FIG. 30E shows a graph of the squeeze film pressure on the substrate of a standard planar electrode, vented CMUT with a ring-shaped fluidic trench. The pull-in voltage of the related configuration was measured at 34.34 V. For the CMUT 510 with a ring-shaped fluidic trench to tune the squeeze film, the pressure on the substrate is reduced to less than 1 / 50 of the pressure in a similar design without a fluidic trench. Optimizing the distribution of the fluidic trench makes the pressure on the substrate uniform, thereby increasing the area of ​​the electrode, increasing the effective capacitance and reducing the pull-in voltage.

[0204] FIG. 30F shows the shape of a deflected two-profile step plate biased with a pull-in voltage of 90%.

[0205] FIG. 30G shows a graph of squeeze film pressure on a substrate for a two-profile step electrode, vented CMUT without a fluidic trench.

[0206] FIG. 30H shows a front view of a trench 517 including a fluidic trench for a CMUT 510 including a two-profile step-electrode CMUT.

[0207] FIG. 30I shows a cross-sectional view of a fluidic trench for a two-profile step-electrode CMUT.

[0208] FIG. 30J shows a graph of the squeeze film pressure on the substrate of a two-profile step electrode, vented CMUT with fluidic trench. The pull-in voltage of the related configuration is measured at 22.85 V, which is 33% lower than the pull-in voltage of the standard planar electrode design. As mentioned above, for the CMUT 510 with a ring-shaped fluidic trench to adjust the squeeze film, the pressure on the substrate is nearly 50 times lower than that of a similar design without a fluidic trench. The distribution of the fluidic trench can be optimized to uniformly distribute the pressure on the substrate, thereby enlarging the area of ​​the electrode and increasing the effective capacitance.

[0209] FIG. 30K shows the configuration of the deflected plate with the tilt electrodes biased at a pull-in voltage of 90%.

[0210] FIG. 30L shows a graph of squeeze film pressure on the substrate of a graded electrode vented CMUT without a fluidic trench.

[0211] FIG. 30M shows a front view of trench 517 including a fluid trench for a CMUT 510 including a graded electrode CMUT.

[0212] FIG. 30N shows a cross-sectional view of a fluidic trench for a graded electrode CMUT.

[0213] Figure 30O shows a graph of the squeeze film pressure on the substrate of a graded electrode vented CMUT with fluidic trench. The pull-in voltage of the related configuration is measured at 17.03 V, which is 50% lower than the pull-in voltage of the standard planar electrode design. By adding and optimizing the ring-shaped fluidic trench to tune the squeeze film, the pressure on the substrate is more than 65 times lower than the pressure of a similar design without a fluidic trench.

[0214] FIG. 30P shows the shape of a deflected plate with curved electrodes biased at a 90% pull-in voltage.

[0215] FIG. 30Q shows a graph of squeeze film pressure on the substrate of a curved electrode vented CMUT without a fluidic trench.

[0216] FIG. 30R shows a front view of trench 517 including a fluidic trench for a CMUT 510 including a curved electrode CMUT.

[0217] FIG. 30S shows a cross-sectional view of a fluidic trench for a curved electrode CMUT.

[0218] Figure 30T shows a graph of the squeeze film pressure on the substrate of a curved electrode vented CMUT with a fluidic trench. The pull-in voltage of the related configuration is 14.49V, which is 56% lower than the pull-in voltage of the standard planar electrode design. By adding and optimizing the ring-shaped fluidic trench to tune the squeeze film, the pressure on the substrate is more than 60 times lower than that of a similar design without a fluidic trench.

[0219] FIG. 30U compares the transmission sensitivity of various electrode shapes for a vented CMUT.

[0220] Figure 30V compares the receiving sensitivity of various electrode shapes for a vented CMUT.

[0221] FIG. 30W compares the transmit sensitivity of various electrode geometries for a vented CMUT with a fluidic trench.

[0222] FIG. 30X compares the receiver sensitivity of various electrode geometries for a vented CMUT with a fluidic trench.

[0223] FIG. 30Y compares the transmission sensitivity and bandwidth of CMUTs with varying fluidic trench heights and DC bias at 90% pull-in voltage. The bandwidth is broadened by introducing squeeze films and controlled by optimizing the fluidic trenches to tune the damping and stiffening effects of the squeeze films. The bandwidth can be tuned over a wide range by adjusting the trench height, simplifying the design, optimization, and fabrication of wide bandwidth airborne CMUTs 510. In some embodiments, the trenches 517 of the inventive concept include one or more trenches with a height (e.g., depth) of at least 1 μm, or 2 μm, and / or a height of 15 μm, 20 μm, 30 μm, or 40 μm or less.

[0224] Referring now to FIG. 31, a cross-sectional view of an embodiment of a CMUT with a shaped dielectric consistent with the inventive concept is shown. The CMUT 510 of FIG. 31 can be of a similar structure and arrangement to the CMUT 510 described with reference to FIG. 1 and elsewhere herein. The CMUT 510 can include a bottom electrode 511 on which a dielectric film 514 and a support 515 are disposed. As shown in FIG. 31, the support 515 and the dielectric film 514 can include one or more similar materials, for example, silicon dioxide. A plate 512 is disposed on the support 515 such that a cavity 513 is formed between the dielectric film 514 and the plate 512. The plate 512 can include a multi-layer structure as shown, for example a structure including a first conductive film 5121a including a conductive material (e.g., doped silicon) and a second conductive film 5121b including another conductive material (e.g., aluminum). Alternatively, the plate 512 can include a single layer structure (e.g., a single layer of doped silicon). The dielectric film 514 may include a non-planar shape (e.g., a contoured shape described herein), for example, a shape in which the edges of the dielectric film 514 are thicker than the center (e.g., closer to the plate 512). The shape of the dielectric film 514 may be selected to optimize the capacitance of the CMUT 510 (e.g., while avoiding impeding the movement of the plate).

[0225] The capacitance of a parallel plate capacitor is expressed as: C=ε rε0A / d where A is the plate area, d is the plate spacing, and ε r is the relative dielectric constant of the dielectric film 514, and ε0 is the vacuum dielectric constant. ins , and the relative dielectric constant between the plates ε r For a capacitor having a .DELTA..times ... d eff =d0+d ins / ε r Therefore, the capacitance is: C=ε0A / d eff

[0226] 31A, a schematic diagram illustrating the capacitance of a CMUT consistent with the concepts of the present invention is shown. S 31A. In the case of a planar bottom electrode 511, a planar dielectric film 514 (not shown), and a planar plate 512, d0+d ins is constant across the cavity area in this model CMUT 510 when the plate is undeflected. In some embodiments, the capacitance C of a segment (e.g., an edge segment) of the CMUT 510 scales with the effective gap height d eff (e.g., at least a 2%, 5%, 10%, 25%, and / or 50% increase). For example, the shaped dielectric film 514 in a segment of the CMUT 510 may be increased by decreasing S By increasing the thickness of ins increases, d0 decreases, and ε r >1 (e.g., for silicon dioxide, ε r = 3.8), the effective gap height d eff decreases.

[0227] 31B and 31C, cross-sectional views of various CMUT components including shaped dielectric films consistent with the concepts of the present invention are shown. S (For example, a dielectric film 514 containing one or more profile steps. S 31C shows a CMUT 510 including a curved dielectric film 514. S In some embodiments, the CMUT 510 includes a curved dielectric film 514. S The shape of approximates the profile of plate 512 when plate 512 is fully deflected.

[0228] The CMUT 510 of FIGS. 31A-31C, and other CMUTs 510 described herein, includes a molded plate 512. S 512, while simultaneously including a non-shaped (e.g., planar) bottom electrode 511. Advantages of this configuration include, but are not limited to, a simplified manufacturing process (e.g., by eliminating the need to etch the bottom electrode 511 to form a contoured or other non-planar shape, or by eliminating the need to place an additional curved support layer for the electrode 511), and / or fabricating all or a portion of the CMUT 510 directly on the integrated circuit (e.g., when the electrode 511 cannot be etched). Avoiding a shaped electrode for the electrode 511 avoids limitations imposed on how close the bottom electrode 511 can be to the plate 512 near the edge of the CMUT 510 (e.g., due to the need for a sufficiently thick dielectric film 514 between the electrode 511 and the plate 512) to prevent dielectric breakdown.

[0229] 32, a cross-sectional view of a CMUT including a multi-layer dielectric consistent with the concepts of the present invention is shown. The CMUT 510 of FIG. 32 includes a dielectric film 514 including a first portion 5141 and a second portion 5142. SThe first portion 5141 may include a thickness determined such that the maximum electric field experienced by the dielectric during operation is a certain percentage of the dielectric strength of the dielectric, e.g., at least 15%, 22%, or 30% of the dielectric strength of the dielectric film, and / or no more than 40%, 50%, 60%, 70%, 77%, or 85% of the dielectric strength of the dielectric film. The first portion 5141 may include one, two, or more different materials, e.g., similar and / or different materials such as silicon oxide and / or silicon nitride. The second portion 5142 may include a thickness determined such that the corners of the portion 5142 do not contact the plate 512 when the plate 512 is maximally deflected. The second portion 5142 may include one, two, or more different materials, e.g., similar and / or different materials such as silicon nitride, hafnium oxide, zirconium silicate, hafnium silicate, and / or zirconium dioxide. The first portion 5141 may include a first material having a first k-value and a first dielectric strength. The first portion 5141 may be disposed between the bottom electrode 511 and the plate 512. The second portion 5142 may include a second material having a second k-value higher than the first k-value of the first portion 5141, e.g., a k-value greater than 3.8, and a second dielectric strength. The second portion 5142 may be disposed near an edge of the plate 512, as shown. In some embodiments, the second material of the second portion 5142 may include a dielectric material having a high k-value, e.g., a k-value greater than 3.8, such as a dielectric material selected from the group consisting of hafnium oxide, zirconium silicate, hafnium silicate, zirconium dioxide, and combinations thereof. The first material of the first portion 5141 may include a dielectric material having a relatively low k-value, such as a dielectric material selected from the group consisting of silicon nitride, silicon oxide, and combinations thereof. In some embodiments, the dielectric film 514 S The film 514 may include a single material, including a dielectric material having a high k value, such as a k value of greater than 3.8. S One or more portions of the insulating film may be deposited using atomic layer deposition (e.g., deposited on the bottom electrode 511 in a CMUT manufacturing process). The portion of the CMUT 510 that includes the second portion 5142 of the insulating film is ε rThe larger the value, the greater the effective gap height d eff may include a larger capacitance C (e.g., at least 2%, 5%, 10%, 25%, and / or 50% larger capacitance) because

[0230] The CMUT 510 of FIG. 32, and other CMUTs 510 described herein, may include a multi-layer dielectric film 514, for example where a first layer includes a high-k dielectric film disposed on a second layer including silicon dioxide. Such an arrangement may provide a number of advantages. For example, a material with high dielectric strength but low dielectric constant may be used as the bottom layer to prevent breakdown, while a material with high dielectric constant but low dielectric strength may be used as the top layer to provide increased capacitance at the edge of the CMUT 510 (e.g., at least 2%, 5%, 10%, 25%, and / or 50% increase).

[0231] 33, a sequence of steps for a method of manufacturing a CMUT with a stepped profile dielectric film consistent with the inventive concept is shown. In step A, oxide is dispensed onto a silicon wafer (bottom electrode 511) via, for example, low pressure chemical vapor deposition (LPCVD). In step B, the oxide deposited in step A is patterned as shown. In step C, additional oxide is dispensed and etched again as shown in step D. In step E, another oxide is dispensed. The resulting oxide shape from steps A to E represents the stepped profile dielectric film 514. S (e.g., a dielectric film 514 including one or more profile steps) and a support 515. In step F, an SOI wafer ("silicon on insulator" wafer) is bonded to the support 515 along with a device layer formation plate 512. In some embodiments, one or more additional deposition profile steps and / or etch profile steps may be repeated to form one or more "profile steps" and / or other desired topological features in the dielectric film 514.

[0232] 34, a sequence of steps for a method of manufacturing a CMUT with a stepped profile bottom electrode and a stepped profile dielectric film consistent with the inventive concept is shown. In step A, oxide is dispensed onto a silicon wafer (bottom electrode 511), for example via LPCVD. In step B, the oxide deposited in step A is patterned as shown. In step C, additional oxide is provided and etched again, as shown in step D. In step E, a thermal oxidation process is performed to oxidize a portion of the silicon wafer to increase the thickness of the oxide film while simultaneously forming the stepped profile of the silicon layer shown in the figure. In step F, the SOI wafer is bonded to the support 515 and the handle and buried oxide are removed to form the plate 512. In some embodiments, one or more additional deposition steps (such as thermal oxidation steps) and / or etching steps may be repeated to form one or more profile steps and / or other desired topological features in the dielectric film 514. Alternatively or additionally, one or more etching-based processes may be used to modify the profile of one or more components of the CMUT 510.

[0233] 35A-35D, there are shown cross-sectional views of analyzed CMUT configurations, consistent with the inventive concepts, and graphs of transmit and receive sensitivity for the illustrated CMUT configurations. Applicants have performed finite element analysis of various CMUT configurations. A standard CMUT part (shown in FIG. 35A) was analyzed, and a molded dielectric film 514 S (shown in FIG. 35B). Both CMUT configurations are radially symmetric (e.g., the CMUT is circular). The CMUT includes a shaped dielectric film 514 SThe CMUTs are identical in all respects except for the presence of an additional molded dielectric material in the arrangement. Each analyzed CMUT includes a plate, a cavity, a dielectric film, and a bottom electrode, as shown in the figure. The plate 512 of each CMUT 510 includes three layers (listed from bottom to top): a 1.1 μm thick highly doped silicon layer, a 250 nm thick aluminum layer, and a 100 nm thick silicon nitride layer. The gap height in the center of each cavity 513 is 275 nm. The dielectric film 514 includes silicon dioxide having a thickness of 150 nm at the center of the CMUT. The molded dielectric CMUT (shown in FIG. 35B) additionally has two profile steps of dielectric on top of the base 150 nm layer (see figure). The first profile step starts at a radius of 9 μm and is 75 nm high. The second profile step starts at a radius of 15 μm and is 175 nm high. The top plate of each CMUT forms the top electrode (eg, plate 512) and the highly doped silicon substrate forms the bottom electrode (eg, electrode 511).

[0234] Both of the above CMUT 510 configurations have the same dimensions of the plate 512 and therefore the same resonant frequency. These CMUT 510 configurations are configured to operate at 5 MHz in water. S The inclusion of a stepped profile provides space for the same maximum possible plate 512 displacement as the standard component configuration, without the plate 512 contacting the dielectric membrane 514. The standard CMUT configuration has a pull-in voltage of 100.4 V, but with the associated shaped dielectric membrane 514 S The configuration has a pull-in voltage of 83.0 V. This 17% reduction in pull-in voltage is advantageous because it lowers the voltage required to operate the CMUT, reducing the risk of dielectric breakdown.

[0235] In FIG. 35C, a graph shows a comparison of the transmission sensitivity (pressure output per applied voltage) of the two CMUT configurations of FIG. 35A and FIG. 35B. In both cases, a DC bias voltage equal to 80% of the pull-in voltage is applied. The molded dielectric membrane 514 SThe arrangement provides a 25% increase in maximum transmit sensitivity over the standard planar dielectric film 514 arrangement.

[0236] In FIG. 35D, a graph shows a comparison of receiver sensitivity (output current per incident pressure) for the two CMUT configurations of FIG. 35A and FIG. 35B. In both cases, a DC bias voltage equal to 80% of the pull-in voltage is applied. The molded dielectric film 514 S The arrangement results in a 25% increase in maximum receive sensitivity over the standard dielectric membrane 514 configuration. In a typical use (such as pulse-echo imaging), the improvement shown in Figures 35C and 35D represents a 56% increase in bidirectional sensitivity when comparing the CMUT configuration of Figure 35B to the CMUT configuration of Figure 35A.

[0237] The applicant has conducted a computer simulation to determine whether the shaped dielectric film 514 S We have discovered that a CMUT 510 configuration including a dielectric film 514 (described herein) provides a strong "catch effect" for the plate when the plate displacement is large or when the device is operated in collapse mode. In other words, when the plate 512 is exposed to a dielectric film 514 (e.g., a dielectric film 514 including a shape that is close to the deflected shape of the plate 512), S ), the force on plate 512 is greater than if dielectric film 514 were planar as in the standard CMUT configuration. This discovery by applicants is advantageous for a number of reasons, as will be explained immediately below.

[0238] For example, when operating in collapse mode, the device can be used with a low (e.g., very low) snapback voltage, so that collapse mode operation can be performed at a very low DC bias voltage. For example, the snapback voltage can be less than 30%, 40%, 50%, or 60% of the pull-in voltage.

[0239] In another example, an electrically adjustable operating frequency with strong spring softening may be used.

[0240] In yet another example, the CMUT510 can be configured as a two-state pre-charged component. The pre-charged CMUT510 can include a built-in bias voltage that is generated by trapping static electricity in place between the top and bottom electrodes. Strong hysteresis due to the catch effect results in a lower snapback voltage, and the same DC bias voltage can be used for both conventional and collapsed modes of operation. The CMUT510 can be switched between the two states by applying a voltage momentarily. Because the CMUT510 has different center frequencies for the collapsed and conventional modes, this technique allows the same device to operate at two different frequencies. This can be useful, for example, in airborne ultrasound applications to switch between a higher frequency, short-range, high-resolution mode and a lower frequency, long-range, low-resolution mode.

[0241] In yet another example, a drive signal including half-wave excitation and / or unipolar pulses and a shaped dielectric film 514 S A combination of a CMUT 510 with a half-wave excitation may be used. For example, the drive signal may include a high-wave excitation arrangement as described in U.S. Patent Application No. US20220152651A1. The catch effect reduces the maximum displacement as a percentage of the gap height that the plate can withstand under conventional sine wave or square wave AC excitation. Half-wave excitation techniques may allow for greater utilization of the gap. For example, half-wave excitation may allow a larger force to be applied to the plate 512 before the plate 512 reaches a peak amplitude, at which point the force may be rapidly reduced to reduce the catch effect.

[0242] In yet another example, various dielectric films 514 S A profile of the shaped dielectric membrane 514 whose profile matches the deflection profile of the plate 512 may be included to optimize sensitivity to pressure, depending on the need for maximum transmit and receive sensitivity to pressure. SIn some cases, the mismatch may not be optimal. Some degree of mismatch may be beneficial to reduce the catch effect. Applicant's modeling has shown that dielectric films 514 with high k values, such as k values ​​greater than 3.8, S In a ring geometry, varying the inner radius of the ring changes the optimized performance between pressure (e.g., maximum pressure) and sensitivity. The ring of dielectric material can be placed in various locations to tailor the displacement profile of the plate 512. Because the force on the plate 512 is higher in the area where the dielectric ring is present, the force profile of the plate 512 can be designed to tailor the displacement profile of the plate.

[0243] In yet another example, the dielectric constant constraint for the dielectric film 514 may be 3.8. r Increasing ε results in increased sensitivity (e.g., at least a 2%, 5%, 10%, 25%, and / or 50% increase). r Further increases in ε increase the strength of the catch effect (e.g., at least 2%, 5%, 10%, 25%, and / or 50% increase) with little additional gain in sensitivity. r may be used to improve sensitivity without excessively increasing the catch effect (e.g., at least 2%, 5%, 10%, 25%, and / or 50% increase in sensitivity). Useful improvements in transmit and / or receive sensitivity can be achieved by increasing ε r This can be achieved with common dielectric materials such as silicon oxide and silicon nitride, where ε is in the range of 3 to 6. Alternatively, r A dielectric with a dielectric constant greater than 6 may be used for part of the insulating film, with a lower dielectric constant material forming the remainder of the insulating film.

[0244] In yet another example, the CMUT 510 may be configured to receive without transmitting, such as when used in an optoacoustic and / or thermoacoustic device (e.g., one or more CMUTs 510 are integrated into a device 100 configured to perform optoacoustic and / or thermoacoustic applications). In these embodiments, maximizing output pressure is not a design goal, and so the functionality of the CMUT 510 may be optimized (e.g., actively optimized) for high sensitivity. High sensitivity may be achieved by using a shaped dielectric membrane 514 having a high k value, e.g., a k value greater than 3.8. S In these embodiments, the gap height can be very low, such as less than 100 nm, but still have a fairly thick dielectric film 514, such as at least 100 nm. Also, in these embodiments, the CMUT 510 can be configured for low bias voltage operation (e.g., up to 20 V, up to 15 V, or up to 10 V), while still achieving high receive sensitivity.

[0245] In yet another example, the CMUT 510 may be configured for use in airborne ultrasonic applications, such as those described herein, which may include ultrasonic flow measurement of gases, gesture sensing, obstacle sensing for automobiles and drones, and / or ultrasonic sensing of compressed gas leaks.

[0246] 36, a sequence of steps for a method of manufacturing a CMUT including a shaped bottom electrode consistent with the inventive concepts is shown. In step A, a silicon wafer is shaped using local oxidation as described herein. In step B, a support 515 is formed using local oxidation. In step C, the support 515 is etched, for example, to define the edges of the CMUT 510 and to create a shaped structure for the dielectric film 514. In step D, the dielectric film 514 is formed, for example, by thermal oxidation. After step D, the CMUT 510 may be completed using one or more bonding techniques, such as fusion bonding.

[0247] CMUT510 is a molded bottom electrode511 S and molded dielectric film 514 SIn some embodiments, the CMUT 510 includes a thick support 515, for example, a support 515 that is thicker than the thickness of the insulating film 514 plus the maximum gap height of the CMUT 510 (e.g., the gap height at the center of the CMUT 510). Increasing the thickness of the support 515 may reduce parasitic capacitance of the CMUT 510. The structure of the CMUT 510 may be configured to achieve the desired transmit and receive sensitivity while reducing parasitic capacitance. As shown, a high profile step of silicon material may be placed around the edges of the CMUT 510 (e.g., instead of the center of the CMUT 510). This placement allows the shaped bottom electrode 511 to be positioned around the edges of the CMUT 510. S and support 515 (e.g., a thickened oxide support). In some embodiments, for example, as described herein, shaped electrode 511 is S and / or molded dielectric film 514 S In embodiments including those of the embodiment of the support 515, the thickness of the support 515 is coupled to the gap height (e.g., the thickness of the support 515 is equal to the sum of the gap height and the thickness of the dielectric film 514). The method of FIG. 36 allows for a support 515 with increased thickness, for example, a thickness greater than 500 nm and / or a thickness of 2 μm or less. This increased thickness may reduce the parasitic capacitance of the support region (e.g., parasitic capacitance is reduced by at least 2%, 5%, 10%, 25%, and / or 50%) and / or reduce the risk of dielectric breakdown. The parasitic capacitance reduces the receive sensitivity of the CMUT 510 by providing a parallel impedance to the circuit ground for the receive current. For the same reason, an increase in the thickness of the support 515 may also increase the power requirements when operating in a transmit mode. The area of ​​the support 515 may contribute significantly to the parasitic capacitance, for example, if the support 515 is relatively thin. The method of FIG. 36 allows for very fine control of the gap height, enabling CMUTs 510 with small gap heights, e.g., gap heights less than 100 nm, to be fabricated for low voltage operation, e.g., less than 100 V.

[0248] Referring now to FIG. 37, a sequence of steps in a method for forming a graded silicon layer consistent with the inventive concept is shown. CMUT transducers such as the CMUT 510 described herein may be fabricated using various microfabrication processes as described herein. The steps shown in FIG. 37 show how a graded silicon layer is fabricated using a LOCOS (Local Oxidation of Silicon) process and a graded silicon oxide mask. Step A shows a graded silicon oxide mask applied to a SOI wafer using, for example, LPCVD. After a thermal oxidation process where the oxidation pattern correlates with the thickness of the silicon oxide mask, the silicon oxide is removed and the remaining SOI wafer contains a graded profile as shown in step B. This graded wafer may be incorporated into the fabrication of the CMUT 510 as described herein, for example as the bottom electrode 511 and / or plate 512.

[0249] Referring now to FIG. 38, a sequence of steps for a method of forming a shaped silicon layer consistent with the inventive concepts is shown. The steps shown in FIG. 38 illustrate how a shaped silicon layer can be fabricated using the LOCOS process and a patterned oxide mask. Step A shows the patterned silicon oxide mask applied to an SOI wafer. After a thermal oxidation process where the oxide pattern correlates with the thickness of the silicon oxide mask, the silicon oxide is removed and the remaining SOI wafer contains a shaped profile as shown in step B. This shaped wafer can be incorporated into the fabrication of a CMUT 510 as described herein, for example as bottom electrode 511 and / or plate 512.

[0250] Referring now to FIG. 39, a sequence of steps for a method of manufacturing a CMUT with a shaped plate consistent with the inventive concept is shown. The steps shown in FIG. 39 illustrate how a CMUT, such as the CMUT 510 described herein, can be manufactured using a sacrificial layer during the process. Step A shows a shaped (e.g., sloped as shown) sacrificial layer deposited on a silicon wafer and patterned as shown. In step B, a metal layer is applied, such as by evaporation and / or sputtering processes. In step C, the top of the metal layer is planarized, such as by chemical mechanical polishing (CMP). In step D, the sacrificial layer and metal layer are patterned to expose a portion of the wafer (e.g., the "anchor" area). In step E, a dielectric material is deposited on the assembly, a portion of the deposited dielectric material is anchored to the wafer at the anchor area, and the dielectric material spreads over the entire top of the metal layer. In step F, the sacrificial layer is removed and the plate 512, including the insulating film 5122 and the conductive film 5121, is peeled off from the bottom electrode 511. The supports 515 extend from the anchor regions to the sides of the plate 512 .

[0251] Referring now to FIG. 40, a sequence of steps for a method of manufacturing a CMUT with a shaped bottom electrode consistent with the inventive concept is shown. The steps shown in FIG. 40 illustrate a method of manufacturing a CMUT, such as the CMUT 510 described herein, using a multi-layer profile step oxide passivation film. In step A, a film of silicon oxide (the "oxide mask") is applied to a silicon wafer, such as by thermal oxidation or LPCVD. In some embodiments, the thickness of the oxide mask is determined based on the desired profile step height resulting from the thermal oxidation of step D. In step B, photoresist is applied, such as by lithography, and the silicon oxide is etched, such as by reactive ion etching (RIE), where there is no photoresist. The thickness of the etched oxide mask can be configured to control the height of features created in the wafer. In step C, additional photoresist is applied and the silicon oxide is etched again. In step D, the assembly is subjected to thermal oxidation, where the oxide mask has delayed the oxidation of the silicon wafer based on the height of the mask. In step E, photoresist is applied and the silicon oxide is etched, such as by buffered oxide etching (BOE). In step F, a final thermal oxidation may be performed to form an insulating film (e.g., dielectric film 514) on the stepped profile silicon wafer. Step F may be performed to form the stepped profile bottom electrode 511 of the CMUT 510 with the dielectric film 514 and the support 515. S A similar process can be used to produce stepped profile plate 512 as described herein. S can be produced.

[0252] Referring now to FIG. 41, a sequence of steps for a method of manufacturing a CMUT with a shaped bottom electrode consistent with the inventive concepts is shown. The steps shown in FIG. 41 illustrate a method of manufacturing a CMUT, such as CMUT 510 described herein, using selective oxidation. In step A, a silicon wafer is patterned as described with reference to FIG. 40 herein. The wafer includes multiple profile steps, and a film of silicon oxide is placed on the wafer as shown in the figure. In step B, a film of silicon nitride is applied, such as by LPCVD. In step C, photoresist is applied and the silicon oxide and silicon nitride films are etched as shown in the figure. In step D, the assembly is subjected to thermal oxidation such that the stepped profile of the silicon wafer now includes a sloped profile, with each profile step having a gradual transition as shown in the figure. In some embodiments, the transition length (e.g., slope) can be precisely controlled by controlling the thickness of the oxide passivation film and / or the oxidation time. In step E, the nitride film is removed, lithography is applied, and the unmasked oxide film is removed, such as via BOE. In step F, a final thermal oxidation may be performed to form an insulating film (e.g., dielectric film 514) on the tilted silicon wafer. Step F may be performed to form the tilted bottom electrode 511 of the CMUT 510 with the dielectric film 514 and the support 515. S A similar process can be used to fabricate the sloping plate 512 as described herein. S can be produced.

[0253] Referring now to FIG. 42, a sequence of steps for a method of manufacturing a CMUT with shaped plates consistent with the inventive concepts is shown. The steps shown in FIG. 42 illustrate a method of manufacturing two CMUT cells, such as CMUT 510 described herein, each including a shaped plate. In step A, the fabrication begins with an SOI wafer. In step B, two recesses (one for each CMUT) are created in the SOI wafer, for example by thermal oxidation and etching, as shown in the figure. In step C, thermal oxidation is performed to create an oxide layer, which is then etched to form the profile shown in the figure. Step C illustrates the fabrication of a simple plate 512 with a single level change (e.g., a single profile step).S 510a and 510b are shown, although various shapes as described herein can be achieved. In step D, the silicon wafer is thermally oxidized to create a film of silicon oxide, and the shaped SOI wafer is inverted and aligned with the silicon wafer. In step E, the two wafers are joined, such as by fusion bonding. In step F, the handle layer and buried oxide layer of the SOI wafer are removed, such as by grinding and etching. In step G, openings are etched through the SOI wafer down to the silicon of the silicon wafer. In step H, aluminum is deposited and patterned to form an array of CMUTs 510a and 510b, two of which are shown. CMUTs 510a and 510b each include a shaped plate 512 as shown. S In some embodiments, additional steps may be performed, such as (additional) passivation steps, metal stacking (e.g., on bond pads) steps, and / or other micro-fabrication steps as described herein.

[0254] Referring now to FIG. 43, a sequence of steps for a method of fabricating a top plate for a CMUT consistent with the inventive concept is shown. The steps shown in FIG. 43 show a method of fabricating two shaped plates for two CMUT cells, such as for two CMUTs 510 described herein, each plate including a profile of multiple profile steps. In step A, fabrication begins with an SOI wafer. In step B, a film of silicon oxide and a film of silicon nitride are deposited on the silicon layer of the SOI wafer, for example by thermal oxidation and LPCVD, respectively. The oxide and nitride films may be patterned as shown. These films may include a mask for the thermal oxidation. In step C, a thermal oxidation is performed, consuming unmasked silicon of the SOI wafer. In step D, the oxide formed by the thermal oxidation is removed. In step E, the oxide and nitride films are patterned again as shown. In step F, another thermal oxidation is performed. In step G, the oxide formed by the thermal oxidation is removed. In step H, the oxide and nitride films are removed. In step I, thermal oxidation is performed to create an oxide film, which is then etched to separate the two plates 512.S 2. Form an assembly as shown in FIG.

[0255] In some embodiments, steps A to I of FIG 43 are replaced with steps A to C of FIG 42. The process shown in FIG 43 S Repeat the process steps to form two profile steps on the contour of plate 512. S In some embodiments, the contour of the profile step created is smoother than the sharp profile step shown in FIG.

[0256] Referring now to FIG. 44, a sequence of steps in a method of fabricating a top plate for a CMUT consistent with the inventive concept is shown. The steps shown in FIG. 44 illustrate a method of fabricating two shaped plates for two CMUTs, such as two CMUTs 510 as described herein, each plate including features realized by grayscale lithography. In step A, the fabrication starts with a SOI wafer. In step B, a layer of photoresist is applied and exposed using grayscale lithography. In step C, the silicon is etched, the depth of the etch depending on the pattern of the grayscale lithography. In step D, a thermal oxidation is performed to form shaped plate 512. S Create the profile shown, including:

[0257] 45A-45D, cross-sectional schematics of various CMUT designs and graphs of CMUT performance consistent with the inventive concepts are shown. FIG. 45A shows a schematic diagram of a CMUT 510, which includes a standard CMUT with a bottom electrode 511 including a planar shape and a plate 512 including a planar shape. The set of dashed lines shown indicate the corresponding deflected shape of the plate 512 when an associated bias voltage is applied to the CMUT 510. The conventional shape shown represents the shape of the plate 512 when a bias voltage below the collapse voltage of the CMUT 510 is applied. The collapsed shape shown represents the shape of the plate 512 when a bias voltage in the range of equal to or greater than the collapse voltage of the CMUT 510 is applied. The deep collapsed shape shown represents the shape of the plate 512 when a bias significantly higher than the collapse voltage is applied, e.g., a bias at least 300% higher than the collapse voltage, e.g., a bias at least 400% higher than the collapse voltage. 45B shows a graph of the resonant frequency of the CMUT 510 versus bias voltage. The changing state of the CMUT 510 is shown as the bias voltage is increased.

[0258] In some embodiments, the CMUT 510 includes a bottom electrode 511 having a non-planar shape, as shown in FIG. S , and / or a plate 512 of a contoured (e.g., non-planar) shape not shown but described herein. S A contoured (e.g. non-planar) shaped bottom electrode 511 S (or plate 512 S ) can be configured to allow the CMUT 510 to operate in multiple collapsed states, each of which requires a lower bias voltage than would be required to reach the “deep collapsed” state of a similar standard CMUT. S may include a stepped profile, as described herein and as shown in FIG. 45C. Alternatively or additionally, the bottom electrode 511 Smay include a curved or other shaped profile, as described herein. In some embodiments, the CMUT 510 includes a bottom electrode 511 and / or a bottom plate 512. S The dashed lines in FIG. 45C show the deflected shape of the plate 512 when a bias voltage is applied to the CMUT 510. The conventional shape shown represents the shape of the plate 512 when a bias voltage lower than the collapse voltage of the CMUT 510 is applied. The first collapse shape shown represents the shape of the plate 512 when a bias voltage of the CMUT 510 is applied that is the first collapse voltage but lower than the second collapse voltage. The second collapse shape shown represents the shape of the plate 512 when a bias voltage higher than the second collapse voltage of the CMUT 510 is applied. FIG. 45D shows a graph of the resonant frequency of the CMUT 510 versus bias voltage. The changing state of the CMUT 510 is shown as the bias voltage is increased.

[0259] Transitions between different collapse modes can result in "jumps" in frequency and electric field, caused by a sudden change in the portion of plate 512 that is allowed to move.

[0260] 45C CMUT 510 may achieve higher operating frequencies and fields while using lower drive voltages by "discrete" the collapse operation. In some embodiments, the system 10 may be configured to allow for variation of the optimal frequency range used during operation (e.g., varying the bias voltage to vary the optimal frequency based on the application of use).

[0261] The system 10 may be configured to switch between the conventional, collapsed, and deep collapsed states described above (e.g., to enable a wide range of operating frequencies with a single device). In some embodiments, the CMUT 510 includes a thick insulating film (e.g., a dielectric film 514, not shown, but described herein) to accommodate high voltages applied, for example, in the deep collapsed state.

[0262] 46A-46N, various examples of component geometries before and after an oxidation process used in the fabrication of CMUTs consistent with the inventive concepts are shown. The illustrated examples are based on localized oxidation of silicon, where a thick oxide film is used as a passivation film to control the oxidation of the silicon. The transition length and curvature of the oxidized silicon can be controlled by varying the thickness of the oxide film. In some embodiments, these methods can be combined with nitride barrier layers and / or multiple profile step silicon substrates to fabricate 3D silicon structures including various shapes (e.g., various heights), multiple profile steps, slopes, and / or curvatures. The illustrated fabrication methods provide extremely precise control of the 3D dimensions and profiles of silicon structures (e.g., microstructures and / or nanostructures), providing unprecedented uniformity across and between wafers, thereby ensuring the fabrication of large-scale CMUT arrays with improved performance (e.g., one or more performance parameters increased by at least 2%, 5%, 10%, 25%, and / or 50%).

[0263] The oxidation of silicon can be nonlinear, such that a thin oxide film (such as a masking layer and / or passivation film) consumes more silicon during the oxidation process than a thicker layer. Thus, silicon structures including multiple profile steps and / or curved profiles can be fabricated using multiple profile step oxide films including various thicknesses. During the oxidation process, transition regions are formed between portions of the oxide film of various thicknesses.

[0264] FIG. 46A shows the silicon substrate prior to oxidation of the 2 μm oxide mask and the resulting structure after the oxidation process, where the silicon substrate includes a stepped profile including transition regions between the profile steps as shown.

[0265] FIG. 46B shows the silicon substrate prior to oxidation of the patterned oxide mask and the resulting structure after the oxidation process, where the silicon substrate includes multiple profile step profiles including transition regions between the profile steps, as shown.

[0266] Figure 46C illustrates a silicon substrate prior to oxidation of the patterned oxide mask and the resulting structure after the oxidation process, where the silicon substrate includes multiple profile step profiles including transition regions between the profile steps as shown. The profile steps illustrated in Figure 46C are shorter (e.g., closer together) than the profile steps illustrated in Figure 46B, resulting in a more "sloped profile" (also referred to as a "graded profile").

[0267] Figure 46D shows the silicon substrate before oxidation of the patterned oxide mask and the resulting structure after the oxidation process. The oxide mask contains separate sections, resulting in an "island" style multiple profile step silicon structure as shown in the figure.

[0268] In some embodiments, a nitride film is used to mask regions of a silicon substrate from unwanted oxidation during the oxidation process. A thick oxide film can be used to control the transition region of the oxidation, with the transition length being related to the thickness of the oxide film. During the fabrication process, the thickness of the oxide film can be selected to control the curvature of silicon structures fabricated using the techniques described herein. For example, Figures 46E-46G show examples of transition differences achievable by varying the oxide film from 1 μm to 3 μm.

[0269] FIG. 46E shows the silicon substrate with 1 μm of oxide and nitride masking the oxide before oxidation, and the resulting structure after the oxidation process.

[0270] FIG. 46F shows a similar structure before and after oxidation with a 2 μm oxide layer.

[0271] FIG. 46G also shows a similar structure before and after oxidation, with a 3 μm oxide layer.

[0272] As shown in FIGS. 46E-46G, the thicker the oxide film, the shorter the transition of the silicon substrate in the post-oxidation structure.

[0273] In some embodiments, multiple oxidation steps may be performed to fabricate a multi-profile silicon substrate, as shown in FIG. 46H.

[0274] FIG. 46H shows a silicon substrate and an oxide film partially masked by a nitride film. After the first oxidation, a first profile step is formed in the silicon substrate. An additional nitride mask is applied to the oxide film before the second oxidation. After the second oxidation, the silicon substrate forms a second profile step as shown in the figure. In some embodiments, the design of the silicon structure after oxidation may include curved structures (e.g., including smooth profiles) by limiting the overlap of the nitride mask in the pre-oxidation step to prevent flat areas from being created in the profile areas of the silicon substrate during oxidation.

[0275] In some embodiments, nitride may be used in combination with thick multiple profile step oxide to form curved and / or semi-graded structures. The nitride and thick oxide may be selected to determine the transition length. The oxide thickness may be limited, for example, by cost, such as to 3 μm or less. The use of nitride in the manufacturing process may extend the transition length in the silicon after oxidation, for example, as shown in FIGS. 46I-L.

[0276] FIG. 46I shows a silicon substrate with 2 μm of oxide partially masked with nitride before oxidation and the resulting structure after the oxidation process, where the silicon has a two-step profile with a sloping transition as shown.

[0277] Figure 46J shows a silicon substrate with 2 μm of oxide partially etched and partially masked with nitride prior to oxidation, and the resulting structure after the oxidation process, where the silicon has a two-step profile with a sloping transition as shown. Different etches prior to oxidation of the oxide can affect the sloping rate of the silicon structure.

[0278] FIG. 46K shows a silicon substrate with multiple profile step oxide layers partially masked with a nitride layer prior to oxidation and the resulting structure after the oxidation process, where the silicon includes multiple profile step structures with graded transitions between the profile steps.

[0279] 46L illustrates a silicon substrate with multiple profile step oxides partially masked with nitride prior to oxidation and the resulting structure after an oxidation process, where the silicon includes a graded transition from a first thickness to a second thickness, the characteristics of the graded transition being defined by the pre-oxidation characteristics of the oxide and nitride as described herein.

[0280] In some embodiments, combining a patterned nitride film and a multi-profile-step oxide film on a multi-profile-step silicon substrate may enable the fabrication of curved and / or sloped silicon structures (e.g., nanostructures and / or microstructures) with various properties. The shape of the nitride and / or oxide films can be tailored to control the curvature and / or slope of the resulting silicon structures, as shown, for example, in Figures 46M-N.

[0281] FIG. 46M shows a multiple profile step silicon substrate with patterned oxide and nitride layers before oxidation and the resulting structure after the oxidation process, where the silicon substrate includes a sloped profile.

[0282] FIG. 46N shows a silicon substrate with multiple profile steps having patterned oxide and nitride layers before oxidation and the resulting structure after the oxidation process, where the silicon substrate includes a varying profile (e.g., a wavy profile).

[0283] 47A-47B, which respectively show top and side views of a CMUT plate including a solid piston consistent with the inventive concepts. Additionally, FIGS. 48A-48B show top and side views of a CMUT plate including a non-solid piston consistent with the inventive concepts. As described herein, a piston-based CMUT may include a plate 512 having a mass piston 518 disposed thereon. In some embodiments, the piston 518 includes a relatively solid structure, as shown, for example, in FIGS. 47A-47B. Alternatively, the piston 518 may include a lattice structure including one or more hollow portions, such as the relief 5181 shown in FIGS. 48A-48B. The piston 518 may include one or more reliefs 5181 that extend vertically across the height of the plate 512 (see FIG. 48A), laterally across the thickness of the piston 518 (see FIG. 48B), or in both directions. The relief 5181 may extend laterally in the x-direction, the y-direction, or both to create a grid pattern of relief 5181 within the piston 518. A piston 518 including both vertical and lateral relief may include a three-dimensional grid pattern. A piston 518 including relief 5181 may increase the stiffness of the plate 512 with less mass than a comparably sized solid piston 518.

[0284] 49, a sequence of steps for a method of fabricating a CMUT with a shaped profile consistent with the inventive concept is shown. Silicon may be shaped using a thermal oxidation process, for example as described herein. The oxidation rate of silicon may be accelerated using a doping process, for example an ion implantation process, a diffusion doping process, or both. The various doping processes may be performed quickly and are well controlled. In addition, a soft mask, such as photoresist, may be used as a doping mask. A diffusion process may be used to redistribute dopants within the silicon, which may smooth out sharp edges or corners due to the doping profile.

[0285] The illustrated process includes multiple ion implantation steps. In each step, different doses and ion beam energies can be used to obtain a desired dopant profile in the silicon substrate. As shown in step A, a mask is applied to the silicon substrate, for example, the bottom electrode 511 of the CMUT 510 described herein. The mask may include a photoresist mask or other mask that does not damage the top surface of the silicon substrate. In some embodiments, a hard mask such as an LPCVD oxide may be used. In step B, an ion implantation process is performed in the silicon substrate to create doped regions under the mask openings. In step C, the mask is removed and a second mask is applied to expose another portion of the silicon substrate. An additional ion implantation process is performed to dope the additional portion of the silicon substrate. In step D, a thermal diffusion process is performed to smooth the gradient of the doping profile. In step E, a thermal oxidation is performed. The highly doped regions of the silicon substrate oxidize faster than the undoped regions, so that the oxidation process creates a shaped profile in the silicon substrate that follows the doping profile. In step F, the oxide is removed and in step G, an insulating film may be applied to the silicon substrate as shown.

[0286] 50, there is shown another sequence of steps for a method of fabricating a CMUT with a shaped profile consistent with the inventive concept. The illustrated process includes a single ion implantation step. By adjusting the open area of ​​the doping mask, the volume and concentration of the dopant may be adjusted. Thermal diffusion may be used to convert the discrete doping pattern into a continuous doping profile. In step A, a doping mask is applied to a silicon substrate. In step B, the mask is patterned to have a different density of open area across the surface of the substrate as shown. In step C, an ion implantation process is performed on the silicon substrate to create the individual doped portions of the substrate. In step D, a thermal diffusion process is performed to smooth the individual doped portions into a continuous doping profile. In step E, a thermal oxidation is performed. The highly doped regions of the silicon substrate oxidize faster than the undoped regions, resulting in the oxidation process creating a shaped profile in the silicon substrate that follows the doping profile. In step F, the oxide is removed, and in step G, an insulating film may be applied to the silicon substrate as shown.

[0287] With respect to components (e.g., parts or assemblies) of the inventive concepts, when a description of the performance or other metric of the component is enabled by a particular feature of the component and is expressed in terms of a percentage increase and / or decrease, it should be understood that the associated increase and / or decrease is relative to a comparison of a component that includes that feature to a component that does not include that feature but is otherwise similar (e.g., similar size, materials of construction, etc.). For example, when describing a CMUT that includes a contoured plate that achieves at least a 10% increase in output pressure, this minimum increase is described in comparison to a similar CMUT (e.g., similar size, materials, shape, etc.) that does not have a similar contoured plate.

[0288] It should be understood that the above-described embodiments serve only as examples, and further embodiments are envisioned. Any feature described herein in relation to any one embodiment may be used alone or in combination with other features described, and may also be used in combination with one or more features of any other embodiment, or in any combination of any other embodiment. Moreover, equivalents and variations not described above may also be used without departing from the scope of the inventive concept as defined in the appended claims.

Claims

1. An electrode; a plate covering the electrode to form a cavity; an insulating film disposed between the plate and the electrode; Equipped with wherein the insulating film is disposed on the plate; wherein the electrodes include contoured electrodes; wherein the insulating film comprises a contoured insulating film; wherein a voltage applied across the electrode and the plate deflects the plate; wherein the cavity includes a non-uniform cavity space between the plate and the electrode, the cavity space being largest in a central region of the plate; Capacitive Micromachined Ultrasonic Transducers (CMUTs).

2. a two-dimensional cross-sectional profile of the contoured electrode comprising a stepped profile; Optionally, a two-dimensional cross-sectional profile of the contoured insulating film matches the two-dimensional cross-sectional profile of the contoured electrode.

3. The CMUT of claim 1 , wherein a two-dimensional cross-sectional profile of the contoured insulating film comprises a stepped profile.

4. The CMUT of claim 1 , further comprising a sensing electrode.

5. The CMUT of claim 1 , wherein the plate comprises a contoured plate.

6. the two-dimensional cross-sectional profile of the contoured plate is one or more of piecewise linear, curved, and stepped; and / or the contoured plate includes one or more of at least one planar portion, at least one concave portion, and at least one convex portion; and / or The CMUT of claim 5 , wherein the CMUT is configured to operate in a collapse mode.

7. The CMUT of claim 1 , wherein the CMUT comprises a piston-based CMUT, and the plate further comprises a piston.

8. the plate comprises a contoured plate, and optionally a two-dimensional cross-sectional profile of the contoured plate is one or more of piecewise linear, curved, and stepped; and / or The CMUT of claim 7 , wherein the CMUT is configured to operate in a collapse mode.

9. The CMUT of claim 1 , wherein the CMUT comprises an air-compatible CMUT further having a vent hole.

10. the plate includes a contoured plate; 10. The CMUT of claim 9, wherein optionally, a two-dimensional cross-sectional profile of the contoured plate is one or more of piecewise linear, curved, and stepped.

11. a fluid trench; Optionally, the air-compatible CMUT comprises a piston-based CMUT, and the plate further comprises a piston.

12. The CMUT of claim 9 , wherein the air-compatible CMUT comprises a piston-based CMUT, and the plate further comprises a piston.

13. the insulating film comprises two or more materials, The CMUT of claim 1 , wherein optionally, the two or more materials comprise different dielectric constants.

14. the CMUT is configured to operate in a collapse mode; Optionally, the CMUT is configured to operate in multiple collapse modes.

15. The CMUT according to claim 1 , further comprising a plate support surrounding the electrode and in contact with the plate.

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