Method and system for fabricating an ultrasonic transducer device - Patents.com

Abstract

Methods and systems useful in the fabrication of ultrasonic transducer devices are described herein. Fabrication of ultrasonic transducer devices may involve manipulation of components with extremely small cross-sectional thickness, which may increase the risk of damage to the components. For example, the application of unintentional forces sufficient to damage such components is a significant risk during fabrication steps. As described herein, the risk of damage to ultrasonic transducer device components with small cross-sectional thickness, such as ultrasonic microelectromechanical systems (MEMS) wafers, may be reduced by, for example, partially or completely coating or filling all or a portion of the component with a stabilizing material before subjecting the component to forces associated with the manipulation of the component during the fabrication process.

Description

[Technical field]

[0001]

[0001] Sensitive components of ultrasonic transducers can be damaged during fabrication using conventional methods and systems, for example, by unintentional bending of the components during the fabrication process. In some cases, the array membrane of an ultrasonic transducer device can be damaged enough that the device becomes unreliable or unusable. Repairing transducer components damaged during fabrication can be time-consuming and expensive. In some cases, transducer array components damaged during fabrication cannot be repaired and the unit must be scrapped, reducing manufacturing yields. In some cases, it cannot be determined until after the device is fully assembled and tested whether an ultrasonic device component was damaged during fabrication to the extent that the ultrasonic transducer device must be scrapped, increasing the cost per unit. Thus, in many cases, ultrasonic device manufacturers using existing ultrasonic device fabrication methods and systems must absorb the cost of lost units for unusable or unreliable devices that have components damaged during fabrication. Therefore, improved systems and methods for fabricating transducer devices are desired. Summary of the Invention [Means for solving the problem]

[0002]

[0002] The fabrication of ultrasonic transducer devices can include the manipulation of delicate device components (e.g., one or more ultrasonic transducer devices at risk of breaking or rupturing due to the application of mechanical forces to the component(s). For example, microelectromechanical system (MEMS) components used in generating and / or receiving ultrasonic wave energy during operation of the ultrasonic transducer device can have one or more cross-sectional dimensions (e.g., cross-sectional thickness) that leave the components susceptible to damage due to forces applied to the components. Existing techniques for ultrasonic transducer device fabrication can include the application of forces to such ultrasonic transducer device components (e.g., during application of the components to a substrate, peeling of the components from a temporary substrate, and / or moving the components from one location to another during fabrication), which can increase the risk of damage (e.g., breaking or rupturing) of the components. In fact, damage to the components during ultrasonic transducer device fabrication can affect the function of the ultrasonic transducer device and can result in large and expensive overall losses in product production.

[0003]

[0003] As described herein, damage to a component during fabrication can be reduced by mechanically stabilizing the component during fabrication. For example, a component can be mechanically stabilized by adding a stabilizing material to the component (e.g., by partially or completely coating or filling all or a portion of the component with a stabilizing material). In some cases, the stabilizing material can be added to the component prior to fabrication steps that include physical manipulation of the component, such as the component relative to a structural support (e.g., a carrier substrate), peeling the component from a structural support, and / or attaching the component to one or more additional device components, for example, to reduce the risk of damage (fracture or breakage of a portion of the component).

[0004] In various aspects, a method of making an ultrasonic transducer device includes forming a plurality of cavities in a transducer wafer bonded to a carrier substrate, contacting one or more interior surfaces of one or more of the plurality of cavities with a stabilizing material, and separating the transducer wafer from the carrier substrate after contacting the one or more interior surfaces with the stabilizing material. In some cases, the method includes reducing a cross-sectional thickness of at least a portion of the transducer wafer. In some cases, the cross-sectional thickness of the transducer wafer is reduced to 75 micrometers or less. In some cases, the cross-sectional thickness of the transducer wafer is reduced to 50 micrometers or less. In some cases, reducing the cross-sectional thickness of at least a portion of the transducer wafer is performed prior to forming the plurality of cavities in the transducer wafer. In some cases, reducing the cross-sectional thickness of at least a portion of the transducer wafer is performed after forming the plurality of cavities in the transducer wafer. In some cases, reducing the cross-sectional thickness of at least a portion of the transducer wafer is performed after contacting the one or more interior surfaces with the stabilizing material. In some cases, reducing a cross-sectional thickness of at least a portion of the transducer wafer is performed prior to contacting one or more inner surfaces with the stabilizing material. In some cases, the cavities are formed in the transducer wafer using photolithography. In some cases, forming the cavities in the transducer wafer includes etching the cavities in the transducer wafer. In some cases, reducing a cross-sectional thickness of at least a portion of the transducer wafer includes backgrinding a surface of the transducer wafer. In some cases, reducing a cross-sectional thickness of at least a portion of the transducer wafer includes etching cavity sidewalls of the transducer wafer. In some cases, the etching includes wet etching or plasma etching. In some cases, the transducer wafer bonded to the carrier includes a cross-sectional thickness of 100 micrometers.In some cases, the transducer wafer bonded to the carrier includes a cross-sectional thickness of 75 micrometers. In some cases, the transducer wafer bonded to the carrier includes a cross-sectional thickness of 50 micrometers. In some cases, contacting the one or more interior surfaces with the stabilizing material includes one or more of spin coating, inkjet deposition, spray deposition, physical vapor deposition (PVD), or chemical vapor deposition (CVD). In some cases, the method further includes polymerizing the stabilizing material. In some cases, polymerizing the stabilizing material is performed after contacting the one or more interior surfaces with the stabilizing material. In some cases, polymerizing the stabilizing material is performed simultaneously with contacting the one or more interior surfaces with the stabilizing material. In some cases, polymerizing the stabilizing material includes exposing the stabilizing material to ultraviolet (UV) light. In some cases, contacting the one or more inner surfaces with the stabilizing material includes filling the one or more cavities with the stabilizing material until the stabilizing material is equal to the height of one or more cavity sidewalls of the one or more cavities. In some cases, contacting the one or more inner surfaces with the stabilizing material includes filling the one or more cavities with the stabilizing material until the stabilizing material exceeds the height of one or more cavity sidewalls of the one or more cavities. In some cases, contacting the one or more inner surfaces with the stabilizing material includes filling the one or more cavities with the stabilizing material until the stabilizing material is less than the height of one or more cavity sidewalls of the one or more cavities. In some cases, the method further includes singulating the transducer wafer into one or more ultrasonic transducer chips comprising a plurality of cavities and the stabilizing material, and coupling an acoustic lens coupled to one or more of the stabilizing material or the transducer chips of the one or more ultrasonic transducer chips.In some cases, the acoustic lens extends over and across each of the one or more cavities. In some cases, the acoustic lens is formed from the same material as the stabilizing material. In some cases, the acoustic lens is formed from a material different from the stabilizing material. In some cases, the acoustic lens is formed from a lens material, and the lens material and the stabilizing material have one or more of a sound speed, an acoustic attenuation, or an acoustic impedance that are substantially the same. In some cases, the method further includes coupling one or more ultrasonic transducer chips singulated from the transducer wafer with the plurality of cavities and the stabilizing material to an application-specific integrated circuit (ASIC). In some cases, the one or more ultrasonic transducer chips are coupled to the ASIC by flip-chip soldering. In some cases, the stabilizing material has a thermal decomposition temperature higher than a reflow temperature of a solder used to couple the one or more ultrasonic transducer chips to the ASIC. In some cases, the method further includes coupling the ASIC to a printed circuit board (PCB). In some cases, the ASIC is bonded to the PCB by wire bonding or by flip-chip soldering. In some cases, the stabilization material has a thermal decomposition temperature higher than a reflow temperature of a solder used to bond the ASIC to the PCB. In some cases, the stabilization material includes silicone. In some cases, the stabilization material includes one or more thermal stabilization additives selected from iron, cerium, and titanium oxide. In some cases, the stabilization material has a thermal decomposition temperature higher than 240° C. In some cases, the ultrasonic transducer device comprises a pMUT transducer. In some cases, the ultrasonic transducer device comprises a cMUT transducer.

[0005] In various aspects, the ultrasonic transducer device comprises: a transducer tip with a plurality of cavities; a stabilizing material in contact with at least a portion of an inner surface of one or more of the plurality of cavities; and an acoustic lens extending over and across the plurality of cavities and formed from a lens material, the lens material and the stabilizing material having one or more of a sound velocity, acoustic attenuation, or acoustic impedance that are substantially the same. In some cases, at least a portion. In some cases, the device further comprises an application specific integrated circuit (ASIC) and a printed circuit board (PCB), the ASIC being coupled to the PCB by a joint comprising solder. In some cases, the thermal decomposition temperature of the stabilizing material is higher than a reflow temperature of the solder. In some cases, the reflow temperature of the solder is 240° C. In some cases, the stabilizing material includes one or more thermal stabilizing additives selected from iron, cerium, and titanium oxide. In some cases, the stabilizing material has low acoustic attenuation. In some cases, the acoustic lens is formed from a material different from the stabilizing material. In some cases, the lens material has a thermal decomposition temperature equal to or greater than the thermal decomposition temperature of the stabilizing material. In some cases, the lens material has a thermal decomposition temperature lower than the thermal decomposition temperature of the stabilizing material. In some cases, the transducer tip has a cross-sectional thickness of no more than 50 micrometers across the entire length and width of the transducer tip. In some cases, the ultrasonic transducer device comprises a pMUT transducer. In some cases, the ultrasonic transducer device comprises a cMUT transducer.

[0006] A better understanding of the features and advantages of the present subject matter may be obtained by reference to the following detailed description, which sets forth illustrative embodiments and the accompanying drawings. [Brief description of the drawings]

[0007] [Figure 1]

[0007] Figure 1A is a schematic diagram showing a portion of an ultrasonic transducer device according to an embodiment.

[0007] Figure 1B is a schematic diagram showing a portion of an ultrasonic transducer device according to an embodiment. [Figure 2A]

[0008] 1 is a schematic flow chart of exemplary steps useful in fabricating an ultrasound transducer device according to an embodiment. [Figure 2B]

[0009] 1 is a schematic flow chart of exemplary steps useful in fabricating an ultrasound transducer device according to an embodiment. [Diagram 3]

[0010] 1 is a schematic flow chart of exemplary steps useful in fabricating an ultrasound transducer device according to an embodiment. [Figure 4]

[0011] 1 is a schematic flow chart of exemplary steps useful in fabricating an ultrasound transducer device according to an embodiment. [Figure 5A]

[0012] 1 is a flow chart of an exemplary method useful in fabricating an ultrasound transducer device according to an embodiment. [Figure 5B]

[0013] 1 is a flow chart of an exemplary method useful in fabricating an ultrasound transducer device according to an embodiment. [Figure 6]

[0014] 1 is a flow chart of an exemplary method useful in fabricating an ultrasound transducer device according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008]

[0015] Methods, systems, and devices useful in reducing the risk of damage to one or more components of an ultrasonic transducer device during device fabrication are described herein. An ultrasonic transducer device may include one or more components that are susceptible to damage (e.g., by fracture or breakage) when a force (e.g., normal force and / or shear force) is applied to one or more components at risk of damage (e.g., at a point of one or more components having a cross-sectional dimension that is 50 micrometers (μm) or less). As described herein, the risk of damage to one or more components of an ultrasonic transducer device may be reduced by mechanically stabilizing one or more components (or a portion thereof) during fabrication. For example, a MEMS wafer that may be made to a thickness (e.g., 50 micrometers or less) during ultrasonic transducer device fabrication that may leave the wafer susceptible to damage may be partially or completely coated or filled with a material (e.g., a stabilizing material) that can mechanically stabilize the MEMS wafer during the fabrication process.

[0009]

[0016] In some cases, the risk of damage to components of an ultrasonic transducer device may be reduced by partially or completely coating or filling the components with a material capable of mechanically stabilizing the components prior to fabrication steps including peeling the components from a solid support and / or prior to application of significant mechanical forces to the wafer (e.g., prior to manipulation of the wafer), as described herein. In some cases, a material may be capable of mechanically stabilizing a component (or a given portion thereof) if it can be used to physically resist bending of the component (e.g., by increasing the effective thickness of all or a portion of the component that is subjected to the force). In some cases, the material used to mechanically stabilize one or more components of an ultrasonic transducer device during fabrication may be selected based on one or more of its material properties, such as melting point, curing time, required curing conditions, ultrasonic transmissibility, viscosity, and / or elastic modulus. In some cases, the material used to form the lens of the ultrasonic transducer device, which may have properties that allow the material to be coated on all or a portion of the component or melted into one or more cavities of the component, may be used to mechanically stabilize one or more components of the ultrasonic transducer device during fabrication. Using a material with such properties to mechanically stabilize a component of the ultrasonic transducer device (e.g., a MEMS wafer or a predetermined portion thereof) can reduce the risk of damage to the component while avoiding significant adverse effects on ultrasonic transmission during operation of the device.

[0010]

[0017] In some cases, the fabrication of an ultrasonic transducer device can include making the components of the device thinner (e.g., by backgrinding and / or etching) relative to the cross-sectional height, width, and / or length of the components. In some cases, components of ultrasonic transducer devices that include thin cross-sectional dimensions (e.g., having cross-sectional heights, lengths, and / or widths of 50 micrometers (μm) or less) can be susceptible to damage, for example, when forces are applied during the fabrication process (e.g., when the components are peeled off from a carrier substrate, attached to one or more additional ultrasonic device components, and attached to one or more additional carrier substrates). overview

[0018] The methods and systems described herein may include one or more ultrasound transducer devices 100 (e.g., ultrasound transducers). The ultrasound transducer device 100 may be used to transmit ultrasound energy to and / or receive ultrasound energy from a target location of a target material, for example, to form an image of the target location of the target material. In some cases, the ultrasound transducer may be useful when imaging biological tissue, for example, to determine a physiological condition of the biological tissue or a subject containing the biological tissue. The ultrasound transducer devices described herein may be portable (e.g., handheld). In some cases, the ultrasound transducer device may be made smaller in size by reducing one or more cross-sectional dimensions (e.g., cross-sectional thickness) of one or more components that make up the ultrasound transducer device. In some cases, reducing the size of the ultrasound transducer device (e.g., by reducing the cross-sectional thickness of one or more ultrasound transducer device components) may make the ultrasound transducer device easier to maneuver. In some cases, increasing the maneuverability of an ultrasound transducer device can make the ultrasound transducer device more portable and / or easier to use during an imaging procedure.

[0011]

[0019] The ultrasonic transducer device 100 may include an ultrasonic transducer wafer 102 (e.g., as shown in FIGS. 1A and 1B). In some cases, the ultrasonic transducer wafer 102 may include a microelectromechanical system (MEMS) transducer. In some cases, the MEMS transducer may be a piezoelectric micromachine ultrasound transducer (pMUT). In some cases, the MEMS transducer may be a capacitive micromachine ultrasound transducer (cMUT). In some cases, the cross-sectional thickness 130 of the ultrasonic transducer wafer 102 or a given portion thereof may significantly affect the likelihood (e.g., risk) of damaging the ultrasonic transducer wafer or a given portion thereof (e.g., a MEMS transducer or a given portion thereof) during fabrication. In many cases, preventing damage to the ultrasonic transducer wafer 102 during fabrication can be important to maintaining the functionality (e.g., including accuracy and / or reliability) of the ultrasonic transducer device 100 comprising the ultrasonic transducer wafer 102.

[0012]

[0020] As shown in FIG. 2A and FIG. 2B, the method of fabricating an ultrasonic transducer device 102 can include providing an ultrasonic transducer wafer 102 (e.g., having an initial cross-sectional thickness 130). In some cases, the ultrasonic transducer wafer 102 can include a metal backing layer 104. In some cases, the method of fabricating an ultrasonic transducer device can include, for example, bonding the ultrasonic wafer 102 to a solid support 108 (e.g., a carrier substrate 108) using an adhesive 106 (e.g., as shown in step 902 of FIG. 2A and FIG. 2B). In some cases, the adhesive used to bond the ultrasonic transducer wafer 102 to the solid support 108 can be a detachable adhesive. Using a detachable adhesive can facilitate peeling of the ultrasonic transducer wafer 102 from the solid support 108 at a later stage of the fabrication method. In some cases, the method of making the ultrasonic transducer device 102 may include providing an ultrasonic transducer wafer 102 (e.g., having an initial cross-sectional thickness 130) that is already bonded to a solid support 108 (e.g., by an adhesive 106 such as a releasable adhesive 106). The solid support (e.g., a carrier substrate) may include, for example, glass or quartz. In some cases, the ultrasonic transducer wafer may include a silicon layer bonded to a metal backing layer. In some cases, the metal backing layer may be bonded directly to the solid support (e.g., between the silicon layer of the ultrasonic transducer wafer and the solid support). In some cases, the ultrasonic transducer wafer or a portion thereof (e.g., the metal backing layer) may be bonded to the solid support by an adhesive (e.g., a releasable adhesive).

[0013]

[0021] The method of fabricating the ultrasonic transducer device 100 can include reducing a cross-sectional thickness of the ultrasonic transducer wafer 102 or a portion thereof (e.g., from an initial cross-sectional thickness 130 to a reduced cross-sectional thickness 131). For example, the method of fabricating the ultrasonic transducer device 100 can include reducing a thickness of a silicon layer of the ultrasonic transducer wafer 102, for example, from an initial cross-sectional thickness 130 to a reduced cross-sectional thickness 131. Reducing the cross-sectional thickness of the ultrasonic transducer wafer 102 can include backgrinding the ultrasonic transducer wafer 102 or a portion thereof (e.g., the silicon layer of the ultrasonic transducer wafer 102). In some cases, reducing the cross-sectional thickness of the ultrasonic transducer wafer 102 can include using photolithography. In some cases, reducing the cross-sectional thickness of the ultrasonic transducer wafer 102 can include etching the ultrasonic transducer wafer 102 or a portion thereof (e.g., using a wet etching or plasma etching technique). In some cases, reducing the cross-sectional thickness of the ultrasonic transducer wafer can improve the functionality of the ultrasonic transducer device (e.g., the quality and / or reliability (e.g., repeatability) of the generation and / or detection of ultrasonic energy waves). In some cases, reducing the cross-sectional thickness of the ultrasonic transducer wafer 102 can help reduce the overall size of the ultrasonic transducer device 100.

[0014]

[0022] In some cases, the method of making the ultrasonic transducer device 100 may include reducing the cross-sectional thickness of the ultrasonic transducer wafer 102 from an initial cross-sectional thickness 130 to a reduced cross-sectional thickness 131 (e.g., as shown in step 904 of FIG. 2A and FIG. 2B and step 702 of FIG. 4). In some cases, reducing the cross-sectional thickness may include reducing the cross-sectional thickness of the entire width and length of the ultrasonic transducer wafer 102 (e.g., as shown in FIG. 2A and FIG. 2B, in some cases where backgrinding is used to reduce the cross-sectional thickness of the ultrasonic transducer wafer 102 prior to cavity formation). In some cases, reducing the cross-sectional thickness of the ultrasonic transducer wafer 102 may include reducing the cross-sectional thickness of one or more portions of the ultrasonic transducer wafer 102 (e.g., as shown in FIG. 4, in which the cross-sectional thickness of the cavity sidewall is reduced after cavity formation of the ultrasonic transducer wafer 102). In some cases, the ultrasonic transducer wafer can include a cross-sectional thickness of 20 micrometers (μm) to 100 micrometers, 20 micrometers to 75 micrometers, 30 micrometers to 75 micrometers, 40 micrometers to 75 micrometers, 50 micrometers to 75 micrometers, or 40 micrometers to 50 micrometers. In some cases, the method of fabricating the ultrasonic transducer device 100 can include providing an ultrasonic transducer wafer 102 (e.g., bonded to a carrier substrate 108) with an initial cross-sectional thickness of greater than 100 micrometers, at least 100 micrometers, at least 75 micrometers, at least 50 micrometers, at least 40 micrometers, at least 30 micrometers, or at least 20 micrometers. In some cases, the method of fabricating the ultrasonic transducer device 100 can include reducing the cross-sectional thickness of the ultrasonic transducer wafer 102 to a cross-sectional thickness (e.g., reduced cross-sectional thickness) of 1 to 100 micrometers. In some cases, the method of fabricating the ultrasonic transducer device 100 can include:This can include reducing the cross-sectional thickness of the ultrasonic transducer wafer 102 to a cross-sectional thickness (e.g., a reduced cross-sectional thickness) of 1 to 50 micrometers. In some cases, reducing the cross-sectional thickness of the ultrasonic transducer wafer 102 can include reducing the cross-sectional thickness to a value of about 1 micrometer to about 120 micrometers. In some cases, reducing the cross-sectional thickness of the ultrasonic transducer wafer 102 may include reducing the cross-sectional thickness to between about 1 micrometer and about 20 micrometers, between about 1 micrometer and about 30 micrometers, between about 1 micrometer and about 40 micrometers, between about 1 micrometer and about 50 micrometers, between about 1 micrometer and about 60 micrometers, between about 1 micrometer and about 75 micrometers, between about 1 micrometer and about 85 micrometers, between about 1 micrometer and about 100 micrometers, between about 1 micrometer and about 110 micrometers, between about 1 micrometer and about 120 micrometers, between about 20 micrometers and about 30 micrometers, between about 20 micrometers and about 40 micrometers, between about 20 micrometers and about 50 micrometers, between about 20 micrometers and about 60 micrometers, between about 20 micrometers and about 75 micrometers, between about 20 micrometers and about 85 micrometers. torr, about 20 micrometers to about 100 micrometers, about 20 micrometers to about 110 micrometers, about 20 micrometers to about 120 micrometers, about 30 micrometers to about 40 micrometers, about 30 micrometers to about 50 micrometers, about 30 micrometers to about 60 micrometers, about 30 micrometers to about 75 micrometers, about 30 micrometers to about 85 micrometers, about 30 micrometers to about 100 micrometers, about 30 micrometers to about 110 micrometers, about 30 micrometers to about 120 micrometers, about 40 micrometers to about 50 micrometers, about 40 micrometers to about 60 micrometers, about 40 micrometers to about 75 micrometers, about 40 micrometers to about 85 micrometers, about 40 micrometers to about 100 micrometers, about 40 micrometers to about 110 micrometers,About 40 micrometers to about 120 micrometers, about 50 micrometers to about 60 micrometers, about 50 micrometers to about 75 micrometers, about 50 micrometers to about 85 micrometers, about 50 micrometers to about 100 micrometers, about 50 micrometers to about 110 micrometers, about 50 micrometers to about 120 micrometers, about 60 micrometers to about 75 micrometers, about 60 micrometers to about 85 micrometers, about 60 micrometers to about 100 micrometers, about 60 micrometers to about 110 micrometers, about 60 micrometers to about 1 20 micrometers, about 75 micrometers to about 85 micrometers, about 75 micrometers to about 100 micrometers, about 75 micrometers to about 110 micrometers, about 75 micrometers to about 120 micrometers, about 85 micrometers to about 100 micrometers, about 85 micrometers to about 110 micrometers, about 85 micrometers to about 120 micrometers, about 100 micrometers to about 110 micrometers, about 100 micrometers to about 120 micrometers, or about 110 micrometers to about 120 micrometers. In some cases, reducing the cross-sectional thickness of the ultrasonic transducer wafer 102 can include reducing the cross-sectional thickness to a value of about 1 micrometer, about 20 micrometers, about 30 micrometers, about 40 micrometers, about 50 micrometers, about 60 micrometers, about 75 micrometers, about 85 micrometers, about 100 micrometers, about 110 micrometers, or about 120 micrometers. In some cases, reducing the cross-sectional thickness of the ultrasonic transducer wafer 102 may include reducing the cross-sectional thickness to at least about 1 micrometer, at least about 20 micrometers, at least about 30 micrometers, at least about 40 micrometers, at least about 50 micrometers, at least about 60 micrometers, at least about 75 micrometers, at least about 85 micrometers, at least about 100 micrometers, at least about 110 micrometers,or at least to a value of about 120 micrometers. In some cases, reducing the cross-sectional thickness of the ultrasonic transducer wafer 102 can include reducing the cross-sectional thickness to a value of at most about 20 micrometers, at most about 30 micrometers, at most about 40 micrometers, at most about 50 micrometers, at most about 60 micrometers, at most about 75 micrometers, at most about 85 micrometers, at most about 100 micrometers, at most about 110 micrometers, or at most 120 micrometers. The method of making the ultrasonic transducer device 100 can have a tolerance of ±10 micrometers, ±5 micrometers, ±1 micrometer, or a value between any two of these values ​​(e.g., a tolerance of 5-10 micrometers, 1-10 micrometers, or 1-5 micrometers) for the cross-sectional thickness to which the ultrasonic transducer wafer 102 can be reduced. In some cases, reducing the cross-sectional thickness of the ultrasonic transducer wafer 102 may increase the risk of damage to the ultrasonic transducer wafer 102 (e.g., by reducing its ability to withstand torque, twisting, or bending forces that may damage portions of the transducer wafer).

[0015]

[0023] In some cases, a method of making an ultrasonic transducer device can include providing an ultrasonic transducer wafer with one or more cavities 110. The cavities 110 of the ultrasonic transducer wafer 102 can aid in the transmission of ultrasonic energy to and / or from an ultrasonic transducer membrane (e.g., diaphragm) of the ultrasonic transducer device 100. For example, the lumen of the cavity 110 (which can be partially or completely filled with a material having low acoustic attenuation, such as the stabilizing material 101) can serve as a conduit or passage for ultrasonic energy to enter or exit the distal end of the ultrasonic transducer device 100 (e.g., via an acoustic lens 114). In many cases, providing one or more such passages (e.g., in the form of one or more cavities 110, each of which may be spatially aligned with and optionally coupled to a pMUT or cMUT transducer element of the ultrasonic transducer device 100) can enable or improve the generation, detection, and / or transmission of ultrasonic energy by the transducer elements of the ultrasonic transducer device 100 (e.g., compared to the use of a wafer without a cavity). (e.g., multiple cavities, e.g., an array). The cavity 110 of the ultrasonic transducer wafer 102 can comprise an inner lumen. The cavity 110 of the ultrasonic transducer wafer 102 can comprise multiple inner surfaces. For example, the cavity 110 of the ultrasonic transducer wafer 102 can comprise a bottom inner surface of the cavity 110 and one or more cavity sidewall inner surfaces. In some cases, the bottom wall of the cavity 110 of the ultrasonic transducer wafer cavity may be actuated (e.g., by one or more piezoelectric actuators, which may be driven by an ASIC and / or computer system) to generate, for example, an ultrasonic energy signal for transmission to the target material.

[0016]

[0024] In some cases, the process of fabricating the ultrasonic transducer device 100 may include forming one or more cavities 110 in the ultrasonic transducer wafer 102 (as shown in step 906 of FIG. 2A and FIG. 2B and step 652 of FIG. 3). In some cases, multiple cavities 110 may be formed in the ultrasonic transducer wafer 102. In some cases, multiple cavities 110 may be formed in the ultrasonic transducer wafer 102 in an array pattern (e.g., the array corresponds to an array of ASICs 116 to which the ultrasonic transducer wafer 102 will be bonded during the fabrication process). In some cases, one or more cavities 110 may be formed in the ultrasonic transducer wafer 102 or a portion thereof (e.g., a silicon layer of the ultrasonic transducer wafer 102) using photolithography. In some cases, photolithography may include the use of a mask or pattern to prevent exposure of unintended areas to photolithography energy. In some cases, one or more cavities 110 may be formed in the ultrasonic transducer wafer 102 by etching the ultrasonic transducer wafer 102 (e.g., a silicon layer of the ultrasonic transducer wafer 102) using, for example, wet etching or plasma etching.

[0017]

[0025] In some cases, reducing the cross-sectional thickness (e.g., height) of the ultrasonic transducer wafer or its cavity sidewalls can help reduce the overall size of the ultrasonic transducer device and / or improve the performance of the MEMS transducer array. In some cases, reducing the cross-sectional thickness of the ultrasonic transducer wafer (e.g., during fabrication) can increase the risk of damage (e.g., fracture or breakage) to the ultrasonic transducer wafer (e.g., during a step of the fabrication process where the transducer wafer is not mechanically supported, e.g., by a carrier substrate). In some cases, reducing the cross-sectional thickness of the ultrasonic transducer wafer 102 can increase the likelihood of fracture or breakage of the ultrasonic transducer wafer 102 or a portion thereof (e.g., the transducer membrane that constitutes the bottom wall of the transducer wafer cavity) during fabrication of the ultrasonic transducer device 100 (e.g., during wafer processing). For example, reducing the cross-sectional thickness of the ultrasonic transducer wafer (e.g., from an initial cross-sectional thickness of 100 micrometers or more to, e.g., 50 micrometers (μm) or less) can make the wafer more flexible, which can increase the likelihood of the ultrasonic transducer wafer or a portion thereof (e.g., the transducer membrane that constitutes the bottom wall of the transducer wafer cavity) breaking or fracturing when the ultrasonic transducer wafer is subjected to more moderate forces, such as those associated with ultrasonic transducer device fabrication, such as debonding the transducer wafer from a carrier substrate and / or transferring the ultrasonic transducer wafer to a different substrate (e.g., ASIC). In some cases, the risk of damage to the ultrasonic transducer wafer 102 during fabrication can depend on the ratio of the wafer's cross-sectional thickness to the wafer's width or length. In some cases, a first ultrasonic transducer wafer 102 having a larger width and / or length and the same cross-sectional thickness compared to a second ultrasonic transducer wafer 102 may have a higher risk of damage during fabrication compared to the second wafer.In some cases, a first ultrasonic transducer wafer 102 having the same length and width dimensions and a smaller cross-sectional thickness compared to a second ultrasonic transducer wafer 102 may have a higher risk of damage during fabrication. In some cases, fabrication of an ultrasonic transducer wafer 102 including a thickness of 300 micrometers or less and a width and / or length of 152.4 mm (6 inches) (or more) may present a significant risk of damage to the wafer during fabrication (during unassisted handling or manipulation of the wafer without the addition of stabilizing material), while fabrication of an ultrasonic transducer wafer 102 including a thickness of 400 micrometers or less and a width and / or length of 203.2 mm (8 inches) (or more) may present a significant risk of damage to the wafer during fabrication (during unassisted handling or manipulation of the wafer without the addition of stabilizing material).

[0018]

[0026] As described herein, the risk of damaging the ultrasonic transducer wafer 102 (e.g., during a step of the fabrication process where the ultrasonic transducer wafer 102 is not mechanically supported) can be reduced by adding a stabilizing material 101 to all or a portion of the ultrasonic transducer wafer 102. For example, the stabilizing material 101 can be used to coat or fill all or a portion of the surface of the ultrasonic transducer wafer with a small cross-sectional thickness (e.g., no more than 50 micrometers) to reduce the risk of damage to the wafer 102 during fabrication. In some cases, the stabilizing material can be added to one or more cavities of the ultrasonic transducer wafer, for example, to mechanically stabilize the wafer 102. For example, the stabilizing material can be used to coat the bottom surface of the ultrasonic transducer wafer cavity (e.g., before the wafer is peeled from the carrier substrate) to add mechanical stability to the wafer 102 that can help resist forces (e.g., torque, twisting, or bending forces) that may be applied to the wafer 102. The addition of a stabilizing material to the cavity or a portion thereof (e.g., the inner surface of the cavity 110, such as the inner surface of the cavity bottom 112) can be particularly beneficial in reducing the risk of damaging the ultrasonic transducer wafer 102, because a portion of a silicon ultrasonic transducer wafer with a reduced cross-sectional thickness (e.g., the bottom wall of a cavity formed during the fabrication method) can have a higher risk of damage (e.g., fracture or breakage) compared to a silicon ultrasonic transducer wafer that does not have a reduced cross-sectional thickness (e.g., a solid polished silicon wafer).

[0019]

[0027] In some cases, one or more surfaces of the ultrasonic transducer wafer 102 may be contacted with (e.g., partially or completely coated with) the stabilization material 101 before the ultrasonic transducer wafer 102 (which may have a cross-sectional thickness of 50 micrometers or less, 40 micrometers or less, 30 micrometers or less, or 20 micrometers or less) is separated from the solid support 108 (e.g., as shown in step 908 of FIG. 2A and FIG. 2B and step 704 of FIG. 4). For example, a method of making the ultrasonic transducer device 100 may include contacting one or more inner surfaces of a cavity 110 (e.g., of a plurality of cavities 110) of the ultrasonic transducer wafer 102 with the stabilization material 101 (e.g., before the wafer 102 is separated from the solid support 108). In some cases, contacting one or more interior surfaces (e.g., of cavity 110) with the stabilizing material includes filling one or more cavities with the stabilizing material until the stabilizing material is equal to the height of one or more cavity sidewalls of the one or more cavities. In some cases, contacting one or more interior surfaces (e.g., of cavity 110) with the stabilizing material includes filling one or more cavities with the stabilizing material until the stabilizing material exceeds the height of one or more cavity sidewalls of the one or more cavities. In some cases, contacting one or more interior surfaces (e.g., of cavity 110) with the stabilizing material includes filling one or more cavities with the stabilizing material until the stabilizing material is less than the height of one or more cavity sidewalls of the one or more cavities. In some cases, contacting one or more surfaces of the ultrasonic transducer wafer 102 with the stabilizing material 101 can reduce the risk of damage to the ultrasonic transducer wafer 102 (due to forces applied to the wafer 102 during fabrication steps following peeling of the wafer 102 from the solid support 108). In some cases, the inner surface of the bottom wall of the cavity 110 of the ultrasonic transducer wafer 102 can be completely coated with the stabilizing material 101.In some cases, the cavity 110 of the ultrasonic transducer wafer 102 may be partially filled with the stabilizing material 101 (e.g., as shown in Figures 2A and 2B, e.g., the stabilizing material 101 covers the entire inner surface of the bottom wall of the ultrasonic transducer wafer 102, but does not contact the entire height of one or more cavity sidewalls 111). In some cases, the cavity 110 of the ultrasonic transducer wafer 102 may be completely filled with the stabilizing material 101 (e.g., the stabilizing material 101 covers the entire inner surface of the bottom wall of the ultrasonic transducer wafer 102 and fills the cavity up to the top of the cavity sidewall 111, e.g., the stabilizing material 101 contacts the entire height of one or more cavity sidewalls 111 of the cavity 110). In some cases, the cavities 110 of the ultrasonic transducer wafer 102 may be overfilled with the stabilizing material 101 (e.g., as shown in FIG. 3, so that the stabilizing material 101 completely fills the cavities 110 and covers the top of one or more cavity sidewalls 111 of the ultrasonic transducer wafer 102). For example, the ultrasonic transducer wafer 102 bonded to the solid support 108 may be reduced in cross-sectional thickness (e.g., by backgrinding), e.g., to a cross-sectional thickness of 50 micrometers or less, before one or more cavities 110 (e.g., an array of cavities 110) are formed in the ultrasonic transducer wafer 102 (e.g., by photolithography using a photolithographic pattern), e.g., as shown in FIG. 3. In some cases, stabilizing material 101 may be added to partially or completely fill one or more of the cavities 110 after the cross-sectional thickness of one or more of the cavity sidewalls 111 has been made to a reduced thickness (e.g., 50 micrometers or less), for example, as shown in Figure 3. In some cases, additional stabilizing material 101 (e.g., having a high thermal decomposition temperature) may be added beyond the thickness of the cavity sidewalls 111 (e.g., as shown in Figure 3), for example, to form a lens.In some cases, the ultrasonic transducer wafer 102 with the stabilizing material 101 added may be separated from the solid support 108, and in some cases, the ultrasonic transducer wafer 102 may be singulated (e.g., by cutting or dicing with a saw or laser). In some cases, one or more cavity sidewalls 111 of a cavity 110 partially or completely filled with the stabilizing material 101 may be reduced in cross-sectional thickness after the stabilizing material 101 is added (e.g., subsequently cured to allow it to solidify), as shown, for example, in step 702 of FIG. 4. For example, one or more cavities 110 formed in an ultrasonic transducer wafer 102 bonded to a solid support 108 may be partially (or completely) filled with the stabilizing material 101 before one or more cavity sidewalls 111 are etched to reduce the cross-sectional thickness of the cavity sidewalls 111 (e.g., to a cross-sectional thickness of 50 micrometers or less). In some cases, additional stabilizing material 101 (e.g., having a high pyrolysis temperature) may be added to completely fill one or more cavities 110 (e.g., to form a lens, as shown in Figures 2B and 4) or to extend beyond one or more cavity sidewalls 111. In some cases, the stabilizing material 101 can help reduce the risk of damage to the ultrasonic transducer wafer 102 when added to one or more surfaces of the ultrasonic transducer wafer 102 until the stabilizing material 101 has a cross-sectional thickness of less than 5 micrometers, at least 5 micrometers, at least 10 micrometers, at least 20 micrometers, at least 30 micrometers, at least 40 micrometers, at least 50 micrometers, greater than 50 micrometers, 5-50 micrometers, 20-50 micrometers, 20-40 micrometers, or 20-30 micrometers (e.g., the cross-sectional thickness is measured after the stabilizing material has solidified).

[0020]

[0028] In some cases, contacting one or more surfaces of the ultrasonic wave (e.g., one or more inner surfaces of the cavity 110) with the stabilizing material can include spin-coating the stabilizing material 101 on the one or more surfaces. In some cases, the spin-coating of the stabilizing material 101 can be performed under vacuum conditions, for example, to reduce or eliminate bubble formation. In some cases, contacting one or more surfaces of the ultrasonic wave (e.g., one or more inner surfaces of the cavity 110) with the stabilizing material can include inkjet deposition of the stabilizing material 101 on the one or more surfaces. In some cases, the inkjet deposition can be performed under vacuum conditions, for example, to reduce or eliminate bubble formation. In some cases, contacting one or more surfaces of the ultrasonic wave (e.g., one or more inner surfaces of the cavity 110) with the stabilizing material can include spray deposition of the stabilizing material 101 on the one or more surfaces. In some cases, contacting one or more surfaces of the ultrasonic (e.g., one or more interior surfaces of the cavity 110) with the stabilizing material can include chemical vapor deposition (CVD) of the stabilizing material 101 on the one or more surfaces. In some cases, contacting one or more surfaces of the ultrasonic (e.g., one or more interior surfaces of the cavity 110) with the stabilizing material can include physical vapor deposition (PVD) of the stabilizing material 101 on the one or more surfaces. In some cases, a mask or pattern can be used to ensure that the stabilizing material 101 is deposited on the intended surfaces and / or to ensure that the stabilizing material 101 is not deposited on unintended surfaces. In some cases, the stabilizing material 101 can be allowed to solidify after being applied to one or more surfaces of the ultrasonic transducer wafer 102. In some cases, the stabilizing material 101 can be actively solidified (e.g., by curing using, for example, exposure to ultraviolet (UV) light) after being applied to one or more surfaces of the ultrasonic transducer wafer 102.Ensuring that the stabilizing material 101 is bubble-free after deposition (e.g., by depositing the stabilizing material 101 under vacuum and / or using techniques such as spray deposition, CVD, or PVD) can ensure that the acoustic properties of the deposited stabilizing material 101 do not adversely affect the transmission of ultrasonic energy through the stabilizing material 101 during operation of the ultrasonic transducer device 100.

[0021]

[0029] In some cases, additional stabilizing material 101 may be added to the ultrasonic transducer wafer 102 to cover one or more surfaces of the ultrasonic transducer wafer 102 and / or a portion of the solidified stabilizing material 101 after the initial deposition of the stabilizing material 101, for example, as shown in FIG. 4. In some cases, the acoustic lens 114 may be formed from the same material as the stabilizing material 101. For example, the stabilizing material 101 added to one or more surfaces of the ultrasonic transducer wafer 102 and / or a portion of the solidified stabilizing material 101 after the initial deposition of the stabilizing material 101 may be formed into an acoustic lens 114. In some cases, the acoustic lens 114 may be bonded to one or more of the ultrasonic transducer chips (e.g., with multiple cavities) singulated from the ultrasonic transducer wafer and / or the stabilizing material 101 (e.g., of the ultrasonic transducer chips singulated from the ultrasonic transducer wafer). In some cases, the acoustic lens 114 can extend across (eg, across and above) one or more of the cavities of the ultrasound transducer wafer or ultrasound transducer chip.

[0022]

[0030] In some cases, the ultrasonic transducer wafer 102 may be separated from the solid support 108 after contacting the ultrasonic transducer wafer 102 with the stabilizing material 101 (e.g., as shown in step 910 of FIG. 2A and FIG. 2B and step 654 of FIG. 3). In some cases, separating the ultrasonic transducer wafer 102 from the solid support 108 may include debonding a debondable adhesive. In some cases, the ultrasonic transducer wafer 102 may be singulated (e.g., into one or more ultrasonic transducer chips, e.g., ultrasonic transducer chips with multiple cavities and stabilizing material formed in the wafer) using a saw or by laser dicing.

[0023]

[0031] The method of making the ultrasonic transducer device 100 may include assembling an ultrasonic transducer wafer 102 including a stabilizing material 101 with one or more additional components of the ultrasonic transducer device 100 (e.g., as shown in step 912 of FIG. 2A and step 914 of FIG. 2B). The ultrasonic transducer wafer 102 (or a predetermined portion of the ultrasonic transducer wafer 102, such as an ultrasonic transducer chip, which may be a singulated portion of the ultrasonic transducer wafer) may be bonded to an application specific circuit (ASIC) 116. As shown in FIG. 2A, the ultrasonic transducer wafer 102 may be bonded to a conductor of a metal layer 117 of the ASIC 116. In some cases, the metal layer 117 of the ASIC 116 may be bonded to a conductor of a metal layer 121 of a PCB 120 by a wire bond 126, and the wire bond 126 may be soldered to each of the metal layers. In some cases, a non-conductive die attach 118 may be disposed between the ASIC 116 and the PCB 120, as shown in FIG. 2A. In some cases, the ultrasonic transducer wafer 102 (or a portion of the ultrasonic transducer wafer 102, such as an ultrasonic transducer chip) may be bonded to the ASIC 116 by flip-chip soldering. As shown in FIG. 2B, the ultrasonic transducer wafer 102 may be bonded to a conductor of a metal layer 117 of the ASIC 116, which may include a through-silicon-via (TSV) connection 122. In some cases, the TSV connection 122 may be bonded to a conductor of a metal layer 121 of the PCB 120 by a joint such as a flip-chip solder 124 (which may be located, for example, in a non-conductive underfill layer 119 disposed between the ASIC and the PCB), as shown in FIG. 2B.

[0024]

[0032] FIG. 5A shows a flow chart of a method 500 for fabricating an ultrasonic transducer device 100 including a stabilizing material 101. The method 500 may include a step 502 of providing a first component (e.g., an ultrasonic transducer wafer 102) coupled to a solid support 108. One or more features (e.g., including one or more cavities 110) may then be formed in the first component using photolithography, as shown in step 504. The stabilizing material 101 may be applied to one or more surfaces of the first component, as shown in step 506. The first component may be peeled (e.g., separated) from the solid support 108, as shown in step 508. The method 500 may also include bonding the first component to a second component (e.g., an ASIC) after applying the stabilizing material to the first component and separating the first component from the solid support, as shown in step 510.

[0025]

[0033] FIG. 5B shows a flow chart of a method 501 for fabricating an ultrasonic transducer device 100 including a stabilizing material 101. The method 501 may include a step 503 of providing a first component (e.g., an ultrasonic transducer wafer 102) coupled to a solid support 108. One or more features (e.g., including one or more cavities 110) may then be formed in the first component using photolithography, as shown in step 505. The stabilizing material 101 may be used to fill one or more cavities of the first component, as shown in step 507. The first component may be peeled (e.g., separated) from the solid support 108, as shown in step 509. The method may also include bonding the first component to a second component (e.g., an ASIC) after applying the stabilizing material to the first component and separating the first component from the solid support, as shown in step 511.

[0026]

[0034] FIG. 6 shows a flow chart of a method 600 for fabricating an ultrasonic transducer device 100 including a stabilizing material 101. The method 600 may include a step 602 of providing a first component (e.g., an ultrasonic transducer wafer 102) coupled to a solid support 108. The first component may be etched or back-grinded to achieve a desired cross-sectional thickness in the first component, as shown in step 604. The stabilizing material 101 may be used to fill one or more cavities in the first component, as shown in step 606. The first component may be peeled (e.g., separated) from the solid support 108, as shown in step 608. The method may also include bonding the first component to a second component (e.g., an ASIC) after applying the stabilizing material to the first component and separating the first component from the solid support, as shown in step 610. Ultrasonic Transducer Device

[0035] An ultrasonic transducer device may include one or more ultrasonic transducers. In many cases, one or more ultrasonic transducers (e.g., and one or more other internal components, such as a MEMS array, an ultrasonic transducer wafer (e.g., a MEMS wafer), an ASIC, and / or a processor) of an ultrasonic system or device may be located within an internal compartment (e.g., an internal space) of the ultrasonic system or device. In some cases, the internal compartment or space of the ultrasonic system may be surrounded (e.g., spatially surrounded) by an outer barrier, which may include a housing and an acoustic lens 114. In some cases, the internal compartment or space of the ultrasonic system may be defined by an outer barrier that surrounds (e.g., spatially surrounds) it. In some cases, the systems, devices, or methods described herein may include a piezoelectric micromachined ultrasonic transducer (pMUT). In some cases, the systems, devices, or methods described herein may include one or more capacitive micromachined ultrasonic transducers (cMUT). Piezoelectric micromachined ultrasonic transducers (pMUTs) can be formed on substrates such as semiconductor wafers (e.g., printed circuit boards, PCBs). pMUT elements built on semiconductor substrates can provide smaller size profiles than traditional bulky transducers having bulkier piezoelectric materials. In some cases, pMUTs may also be less expensive to manufacture and / or may enable less complex and higher performance interconnects between the transducer and additional electronic components of an ultrasonic device or system.

[0027]

[0036] Micromachined ultrasonic transducers (MUTs), which may include pMUTs and / or cMUTs, may include a diaphragm (e.g., a thin film attached to one or more portions of an interior of an imaging device (e.g., an ultrasound probe), e.g., at a membrane edge). In contrast, traditional bulk piezoelectric (PZT) elements typically consist of a single solid piece of material. Such traditional PZT ultrasonic systems and devices can be expensive to fabricate, for example, because of the high precision required to cut and mount the PZT or ceramic materials that make up the PZT ultrasonic systems and devices at the proper intervals. Additionally, traditional PZT ultrasonic systems and devices can have a significantly higher transducer impedance compared to the impedance of the transmit / receive electronics of the PZT systems and devices, which can adversely affect performance.

[0028]

[0037] In some cases, one or more transducer elements may be configured to transmit and / or receive signals at a particular frequency or bandwidth (e.g., the bandwidth is related to the center frequency). In some cases, one or more transducer elements may be further configured to transmit and / or receive signals at additional center frequencies and bandwidths. Such multi-frequency transducer elements may be referred to as multi-modal elements and may be used in some embodiments to extend the bandwidth of the imaging system or device 100. The transducer elements or pixels may be configured to emit (e.g., transmit) and / or receive ultrasound energy (e.g., ultrasound waveforms, patterns, or pressure waves) at an appropriate center frequency, for example, between 0.1 megahertz (MHz) and 100 MHz. In some cases, the transducer or pixel may be 0.1MHz to 1MHz, 0.1MHz to 1.8MHz, 0.1MHz to 3.5MHz, 0.1MHz to 5.1MHz, 0.1MHz to 10MHz, 0.1MHz to 25MHz, 0.1MHz to 50MHz, 0.1MHz to 100MHz, 1MHz to 1.8MHz, 1MHz to 3.5MHz, 1MHz to 5.1MHz, 1MHz to 10MHz, 1MHz to 25MHz, 1MHz to 50MHz, 1MHz to 100MHz, 1.8MHz to 3.5MHz, 1.8MHz to 5.1MHz, 1.8MHz to 10MHz, 1.8MHz to 25MHz, The ultrasonic transducer may be configured to transmit or receive ultrasonic energy at a center frequency of 1.8 MHz, 1.8 MHz to 50 MHz, 1.8 MHz to 100 MHz, 3.5 MHz to 5.1 MHz, 3.5 MHz to 10 MHz, 3.5 MHz to 25 MHz, 3.5 MHz to 50 MHz, 3.5 MHz to 100 MHz, 5.1 MHz to 10 MHz, 5.1 MHz to 25 MHz, 5.1 MHz to 50 MHz, 5.1 MHz to 100 MHz, 10 MHz to 25 MHz, 10 MHz to 50 MHz, 10 MHz to 100 MHz, 25 MHz to 50 MHz, 25 MHz to 100 MHz, or 50 MHz to 100 MHz.In some cases, the transducer or pixel may be configured to transmit or receive ultrasonic energy at a center frequency of 0.1 MHz, 1 MHz, 1.8 MHz, 3.5 MHz, 5.1 MHz, 10 MHz, 25 MHz, 50 MHz, or 100 MHz. In some cases, the transducer or pixel may be configured to transmit or receive ultrasonic energy at a center frequency of at least 0.1 MHz, 1 MHz, 1.8 MHz, 3.5 MHz, 5.1 MHz, 10 MHz, 25 MHz, 50 MHz, or 100 MHz. In some cases, the transducer or pixel may be configured to transmit or receive ultrasonic energy at a center frequency of at most 0.1 MHz, 1 MHz, 1.8 MHz, 3.5 MHz, 5.1 MHz, 10 MHz, 25 MHz, 50 MHz, or 100 MHz. joint

[0038] A first component of an ultrasonic transducer device (e.g., a printed circuit board or a portion thereof) may be coupled to one or more second components of the ultrasonic transducer device by a joint. In some cases, the joint may provide an electrical connection between the first component and the one or more second components. For example, the joint may in some cases electrically couple the first component to the one or more second components. The joint coupling the first component of the ultrasonic device and the one or more second components of the ultrasonic device may be electrically conductive (e.g., the joint comprises a conductor). For example, the joint may include a conductive material. In some cases, the joint may physically join the first component and the second component and / or stabilize the joint between them.

[0029]

[0039] The junctions of the ultrasonic transducer device may comprise one or more wires (e.g., one or more wire bonds). In some cases, a first end of the wire bond may be coupled to a terminal of the ASIC and a second end of the wire bond may be coupled to a printed circuit board (PCB). In some cases, the wire bond may be coupled to one or more other components of the ultrasonic transducer device (e.g., the ASIC and / or the PCB) by soldering. In some cases, the wire may comprise a conductor. For example, the wire may comprise a copper wire, a gold wire, a silver wire, an aluminum wire, or an alloy thereof (e.g., a magnesium-aluminum or silicon-aluminum wire). In some cases, the wire may be coated (e.g., a palladium-coated wire) and / or doped (e.g., a wire doped with beryllium).

[0030]

[0040] The ultrasonic transducer device may include one or more "through-silicon via" (TSV) connections. In some cases, the TSV connections may electrically couple the ASIC to the PCB. In some cases, the TSVs may be coupled to one or more additional components of the ultrasonic transducer device by a soldering method such as flip-chip soldering. The TSV connections may include a conductive material passing from a first (e.g., distal) surface of a wafer (e.g., a silicon wafer of an integrated circuit such as an ASIC wafer) to a second (e.g., proximal) surface of the wafer. In some cases, the bond may include solder (e.g., at one or more solder points of the TSV connections or wirebond connections).

[0031]

[0041] The joints of the ultrasonic transducer device can include solder. The solder can be useful for stabilizing or connecting one or more other components of the joint (e.g., wire bonds, TSVs, and / or metal layers of an ASIC or PCB). The solder can have a reflow temperature. In some cases, the solder can melt from a solid phase to a liquid or semi-liquid phase when its temperature reaches the reflow temperature. In some cases, the method for making the ultrasonic transducer device can include bringing all or a portion of the ultrasonic transducer device to a temperature equal to the reflow temperature of the solder (e.g., to melt the solder for application to the joint). In some cases, the method for making the ultrasonic transducer device can include maintaining the ultrasonic transducer device and / or one, more, or all of its components at a temperature(s) substantially equal to or lower than (e.g., not exceeding) the reflow temperature. In some cases, the reflow temperature of the solder can be up to 240°C. stabilizing material

[0042] As described herein, the occurrence of damage sustained to ultrasonic device components during fabrication can be significantly reduced by specifying the materials, methods, and / or order of steps used in fabricating the ultrasonic transducer device 100. For example, adding (e.g., partially or completely coating or filling) a material (e.g., stabilizing material 1010) to one or more surfaces or cavities of the ultrasonic transducer wafer 102 (e.g., before the ultrasonic transducer wafer 102 is removed from the solid support to which it is bonded) can significantly reduce the likelihood and / or extent to which the ultrasonic transducer wafer 102 is damaged during fabrication. In some cases, all or a portion of the ultrasonic transducer wafer 102 may be brought to (e.g., reduced to) a desired cross-sectional thickness (e.g., by grinding), etched to provide a desired surface architecture (e.g., using lithographic technique(s) to create transducer cavities 110), and contacted with (e.g., partially or completely coated or filled with) a material (e.g., stabilizing material 101) capable of stabilizing the ultrasonic transducer wafer 102 prior to removing the wafer 102 from the solid support 108. For example, the ultrasonic transducer wafer 102 may be etched to provide a desired architecture (e.g., comprising a plurality of cavities 110) and partially filled with a material capable of stabilizing the processed array prior to modifying the thickness of the transducer wafer 102 (e.g., thinning the cavity walls to a desired thickness, e.g., by lithography).

[0032]

[0043] In some cases, the stabilizing material 101 can be a material capable of flowing onto or into a surface or feature of the component. For example, the stabilizing material can be melted and applied to a surface of the component (e.g., an interior surface of a cavity 110 of the component, such as an inner surface of a bottom wall 112 of the cavity 110 of the ultrasonic transducer wafer 102, or a surface of a cavity sidewall 111) and allowed to cure (e.g., harden or dry) before the component undergoes an operational step of the fabrication process. In some cases, the stabilizing material can be a flowable material that is applied to a surface of the component (e.g., an interior surface of a cavity of the component) and cured (e.g., using ultraviolet light) before the component undergoes an operational step of the fabrication process. In some cases, applying a stabilizing material to all or a portion of the ultrasonic transducer wafer 102 can reduce the risk of damage to the ultrasonic transducer wafer 102 (e.g., as a result of forces experienced by the ultrasonic transducer wafer 102 during fabrication of the ultrasonic transducer device 100), for example, if all or a portion of the ultrasonic transducer wafer 102 (e.g., to which the stabilizing material 101 is applied) has a reduced cross-sectional thickness (e.g., a cross-sectional thickness of 50 micrometers or less, 40 micrometers or less, 30 micrometers or less, or 20 micrometers or less).

[0033]

[0044] In some cases, the stabilizing material 101 can meet or exceed the acoustic requirements of the acoustic lens 114 used in the ultrasonic transducer device 100. In some cases, the stabilizing material 101 can have a sound velocity that is higher than or substantially the same as the sound velocity of the material used to form the acoustic lens 114. In some cases, the stabilizing material 101 can have an acoustic attenuation that is lower than or substantially the same as the acoustic attenuation of the material used to form the acoustic lens 114. In some cases, the stabilizing material 101 can have an acoustic impedance that is lower than or substantially the same as the acoustic impedance of the acoustic lens 114. In some cases, the stabilizing material 101 can be used to form the acoustic lens 114 of the ultrasonic transducer device 100 described herein.

[0034]

[0045] The stabilizing material 101 may include a monomer. In some cases, the stabilizing material 101 may include a silicone (e.g., a silicone-based monomer). In some cases, the stabilizing material 101 may include a polymer. In some cases, the monomers of the stabilizing material 101 may be polymerized to become a polymer. Polymerizing the stabilizing material 101 may include cross-linking all or a portion of the molecules (e.g., monomers) that make up the stabilizing material 101. In some cases, the monomers of the stabilizing material 101 may be polymerized by exposing the stabilizing material 101 to ultraviolet (UV) light (e.g., light having a wavelength between 315 nanometers and 430 nanometers). In some cases, the stabilizing material 101 may be polymerized using a polymerization agent or catalyst (e.g., a UV-activated platinum catalyst). For example, the stabilizing material 101 may be polymerized in some cases by mixing the stabilizing material 101 with a polymerization initiator. In some cases, polymerizing the stabilizing material 101 can partially or completely harden the stabilizing material (e.g., the stabilizing material 101 can be solidified or partially or completely transitioned from a liquid state to a solid state or from a semi-solid state to a solid state). In some cases, polymerizing the stabilizing material 101 can be performed simultaneously with contacting the ultrasonic transducer wafer 102 (or a portion thereof) with the stabilizing material 101. In some cases, polymerizing the stabilizing material 101 can be performed after contacting the ultrasonic transducer wafer 102 (or a portion thereof) with the stabilizing material 101.

[0035]

[0046] In some cases, the stabilizing material 101 may undergo a curing or polymerization process (e.g., including exposure to UV light) for a curing time. The curing time may depend on the composition and / or amount of the stabilizing material 101 being cured (or polymerized). For example, curing conditions including exposing the stabilizing material 101 to ultraviolet light may include exposing the stabilizing material 101 to ultraviolet light for 1 hour or less, 30 minutes or less, 15 minutes or less, 10 minutes or less, 5 minutes or less, 4 minutes or less, 3 minutes or less, 2 minutes or less, 1 minute or less, 45 seconds or less, 30 seconds or less, 15 seconds or less, 10 seconds or less, 5 seconds or less, or 1 second or less. In some cases, curing or polymerizing the stabilizing material 101 may include increasing the temperature of the stabilizing material 101. In some cases, increasing the temperature of the stabilizing material 101 may be an advantageous curing condition, for example, in some cases, the curing or polymerization process may be carried out more rapidly at the increased temperature. In some cases, curing or polymerizing the stabilizing material 101 can be performed at a temperature between 100° C. and 18° C., between 80° C. and 20° C., between 80° C. and 25° C., between 80° C. and 35° C., between 80° C. and 45° C., between 80° C. and 55° C., between 80° C. and 65° C., between 60° C. and 20° C., between 60° C. and 25° C., between 60° C. and 35° C., or between 60° C. and 45° C. In some cases, curing or polymerizing the stabilizing material 101 can include increasing the humidity (e.g., beyond ambient humidity) in the environment of the stabilizing material 101 during the polymerization or curing step, for example, to increase the rate of curing or polymerization. In some cases, curing or polymerizing the stabilizing material can include decreasing the oxygen content (e.g., beyond ambient oxygenation) in the environment of the stabilizing material 101 during the polymerization or curing step, for example, to increase the rate of curing or polymerization.

[0036]

[0047] In some cases, the step of polymerizing the stabilizing material 101 (e.g., the stabilizing material 101 is exposed to UV light) may be performed after contacting one or more inner surfaces of the ultrasonic transducer wafer 102 (e.g., one or more surfaces of the cavities 110 of the ultrasonic transducer wafer 102) with the stabilizing material 101 (e.g., the stabilizing material 101 includes a monomer, such as a silicone-based monomer). In some cases, the step of polymerizing the stabilizing material 101 (e.g., the stabilizing material 101 is exposed to UV light) may be performed during the step of contacting one or more inner surfaces of the ultrasonic wafer 102 (e.g., one or more surfaces of the cavities 110 of the ultrasonic transducer wafer 102) with the stabilizing material 101 (e.g., the stabilizing material 101 includes a monomer, such as a silicone-based monomer).

[0037]

[0048] The stabilizing material 101 can include silicone. In some cases, the stabilizing material 101 can include one or more additives (e.g., thermally stable additives). In some cases, the stabilizing material 101 including one or more additives (e.g., one or more thermally stable additives) can have a higher thermal decomposition temperature. In some cases, by adding one or more additives (e.g., thermally stable additives) to the stabilizing material 101, it is possible to increase the thermal decomposition temperature of the stabilizing material by up to 10° C., up to 20° C., up to 30° C., up to 40° C., up to 50° C., up to 60° C., up to 70° C., up to 80° C., up to 90° C., up to 100° C., up to 110° C., or up to 120° C. In some cases, the stabilized material 101 includes one or more additives (e.g., thermally stable additives) to have a thermal decomposition temperature of up to 180° C., up to 200° C., up to 210° C., up to 220° C., up to 230° C., up to 240° C., up to 250° C., up to 260° C., up to 270° C., up to 280° C., or higher than 280° C. In some cases, the stabilized material 101 includes one or more additives (e.g., thermally stable additives) to have a thermal decomposition temperature of greater than 180° C., greater than 200° C., greater than 210° C., greater than 220° C., greater than 230° C., greater than 240° C., greater than 250° C., greater than 260° C., greater than 270° C., or greater than 280° C. Some thermally stable additives useful in the stabilized material 101 include iron, cerium, and titanium oxide. In some cases, the thermally stable additives can have a particle size of 10 micrometers or less.

[0038]

[0049] In many cases, materials used to form acoustic lenses in existing ultrasonic transducer devices have a thermal decomposition temperature lower than the solder reflow temperature. In many cases, a stabilization material 101 having a thermal decomposition temperature higher than the solder reflow temperature (e.g., of the solder used in the fabrication of the ultrasonic transducer device 100) can be used in the methods and systems described herein. In some cases, using a stabilization material 101 having a thermal decomposition temperature higher than the solder reflow temperature can reduce the risk that the stabilization material is adversely affected (e.g., in terms of acoustic clarity and / or melting) by the ultrasonic transducer device fabrication steps following the addition of the stabilization material to the ultrasonic transducer wafer. For example, using a stabilization material 101 having a thermal decomposition temperature higher than the reflow temperature of the solder used to bond the ASIC to the PCB after the stabilization material 101 is added to the ultrasonic transducer wafer 102 can prevent the stabilization material 101 from melting or degrading when heat is applied to bond the ASIC to the PCB during fabrication.

[0039]

[0050] The stabilizing material 101 can exhibit low acoustic attenuation (e.g., after being added to a silicon-based wafer or a predetermined portion thereof and cured). For example, the stabilizing material 101 can have an acoustic attenuation of about 0.10 decibels per millimeter (dB / mm) to about 50.0 dB / mm. In some cases, the stabilizing material 101 has a refractive index of about 0.10 dB / mm to about 0.25 dB / mm, about 0.10 dB / mm to about 0.50 dB / mm, about 0.10 dB / mm to about 0.75 dB / mm, about 0.10 dB / mm to about 1.00 dB / mm, about 0.10 dB / mm to about 5.00 dB / mm, about 0.10 dB / mm to about 10.0 dB / mm, about 0.10 dB / mm to about 15.0 dB / mm, about 0.10 dB / mm to about 20.0 dB / mm, about 0.10 dB / mm to about 25.0 dB / mm, about 0.10dB / mm to 30.0dB / mm, 0.10dB / mm to 50.0dB / mm, 0.25dB / mm to 0.50dB / mm, 0.25dB / mm to 0.75dB / mm, 0.25dB / mm to 1.00dB / mm, 0.25dB / mm to 5.00dB / mm, 0.25dB / mm to 10.0dB / mm, 0.25dB / mm to 15.0dB / mm, 0.25dB / mm to 20.0dB / mm, 0.25dB / mm to 25.0dB / mm m, approx. 0.25dB / mm to approx. 30.0dB / mm, approx. 0.25dB / mm to approx. 50.0dB / mm, approx. 0.50dB / mm to approx. 0.75dB / mm, approx. 0.50dB / mm to approx. 1.00dB / mm, approx. 0.50dB / mm to approx. 5.00dB / mm, approx. 0.50dB / mm to approx. 10.0dB / mm, approx. 0.50dB / mm to approx. 15.0dB / mm, approx. 0.50dB / mm to approx. 20.0dB / mm, approx. 0.50dB / mm to approx. 25.0dB / mm, approx. 0.50dB / mm to approx. 30.0dB B / mm, approx. 0.50dB / mm to approx. 50.0dB / mm, approx. 0.75dB / mm to approx. 1.00dB / mm, approx. 0.75dB / mm to approx. 5.00dB / mm, approx. 0.75dB / mm to approx. 10.0dB / mm, approx. 0.75dB / mm to approx. 15.0dB / mm, approx. 0.75dB / mm to approx. 20.0dB / mm, approx. 0.75dB / mm to approx. 25.0dB / mm, approx. 0.75dB / mm to approx. 30.0dB / mm, approx. 0.75dB / mm to approx. 50.0dB / mm, approx. 1.00dB / mm to approx. 5.00dB / mm, approx. 1.00dB / mm to approx. 10.0dB / mm, approx. 1.00dB / mm to approx. 15.0dB / mm, approx. 1.00dB / mm to approx. 20.0dB / mm, approx. 1.00dB / mm to approx. 25.0dB / mm, approx. 1.00dB / mm to approx. 30.0dB / mm, approx. 1.00dB / mm to approx. 50.0dB / mm, approx. 5.00dB / mm to approx. 10. 0dB / mm, 5.00dB / mm to 15.0dB / mm, 5.00dB / mm to 20.0dB / mm, 5.00dB / mm to 25.0dB / mm, 5.00dB / mm to 30.0dB / mm, 5.00dB / mm to 50.0dB / mm, 10.0dB / mm to 15.0dB / mm, 10.0dB / mm to 20.0 dB / mm, approx. 10.0dB / mm to approx. 25.0dB / mm, approx. 10.0dB / mm to approx. 30.0dB / mm, approx. 10.0dB / mm to approx. 50.0dB / mm, approx. 15.0dB / mm to approx. 20.0dB / mm, approx. 15.0dB / mm to approx. 25.0dB / mm, approx. 15.0dB / mm to approx. 30.0dB / mm, approx. 15.0dB / mm to approx. 50.0dB / mm B / mm, about 20.0 dB / mm to about 25.0 dB / mm, about 20.0 dB / mm to about 30.0 dB / mm, about 20.0 dB / mm to about 50.0 dB / mm, about 25.0 dB / mm to about 30.0 dB / mm, about 25.0 dB / mm to about 50.0 dB / mm, or about 30.0 dB / mm to about 50.0 dB / mm. In some cases, the stabilization material 101 can have an acoustic attenuation of about 0.10 dB / mm, about 0.25 dB / mm, about 0.50 dB / mm, about 0.75 dB / mm, about 1.00 dB / mm, about 5.00 dB / mm, about 10.0 dB / mm, about 15.0 dB / mm, about 20.0 dB / mm, about 25.0 dB / mm, about 30.0 dB / mm, or about 50.0 dB / mm. In some cases, the stabilization material 101 has a linearity of at least about 0.10 dB / mm, at least about 0.25 dB / mm, at least about 0.50 dB / mm, at least about 0.75 dB / mm, at least about 1.00 dB / mm, at least about 5.00 dB / mm, at least about 10.0 dB / mm, at least about 15.0 dB / mm, at least about 20.0 dB / mm, at least about 25.0 dB / mm, at least about 30.0 dB / mm, or at least about 50.0 dB / mm. In some cases, the stabilizing material 101 can have an acoustic attenuation of at most about 0.10 dB / mm, at most about 0.25 dB / mm, at most about 0.50 dB / mm, at most about 0.75 dB / mm, at most about 1.00 dB / mm, at most about 5.00 dB / mm, at most about 10.0 dB / mm, at most about 15.0 dB / mm, at most about 20.0 dB / mm, at most about 25.0 dB / mm, at most about 30.0 dB / mm, or at most about 50.0 dB / mm. A stabilizing material 101 having low acoustic attenuation (e.g., after doping to at least a portion or a predetermined portion of a silicon-based wafer) can improve the transmission of acoustic (e.g., ultrasonic) energy waves through the stabilizing material 101, for example, during operation of the ultrasonic transducer device 100. application

[0051] In some cases, the imaging system or device 100 described herein may be used in medical imaging, lithotripsy, localized tissue heating for therapeutic intervention, highly intensive focused ultrasound (HIFU) surgery, and / or non-medical flow measurement in pipes (or speaker and microphone arrays). In some cases, the imaging system or device described herein may be used to determine the direction and / or velocity of fluid flow (e.g., blood flow) in arteries and / or veins, for example, using Doppler mode imaging. In some cases, the imaging system or device described herein may be used to determine tissue stiffness.

[0040]

[0052] In some cases, the imaging system or device 100 described herein may be configured to perform one-dimensional imaging (e.g., A-scan imaging). In some cases, the imaging system or device 100 described herein may be configured to perform two-dimensional imaging (e.g., B-scan imaging). In some cases, the imaging system or device 100 described herein may be configured to perform three-dimensional imaging (e.g., C-scan imaging). In some cases, the imaging system or device 100 described herein may be configured to perform Doppler imaging. In some cases, the imaging system or device 100 described herein may be switched into (e.g., between) different modes, including a linear mode or a sector mode. In some cases, the imaging system or device 100 may be electronically configured under programmatic control (e.g., by a user).

[0041]

[0053] In many cases, the imaging system or device 100 (e.g., a probe of the imaging system or device 100) can be portable. For example, the imaging system or device 100 can include a handheld casing (e.g., contained within a housing), which can house one or more transducer elements, pixels or arrays, ASICs, control circuitry, and / or computing devices. In some cases, the imaging system or device 100 can include a battery. Some regulations

[0054] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this subject matter belongs.

[0042]

[0055] As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Any reference herein to "or" is intended to include "and / or" unless otherwise stated.

[0043]

[0056] References throughout this specification to "some embodiments," "further embodiments," or "particular embodiments" mean that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment. Thus, the appearances of the phrases "in some embodiments," or "in further embodiments," or "in particular embodiments" in various places throughout this specification do not necessarily all refer to the same embodiment. Furthermore, particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0044]

[0057] While preferred embodiments of the present subject matter have been shown and described herein, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the present subject matter. It should be understood that various alternatives to the embodiments of the present subject matter described herein may be used in practicing the present subject matter.

Claims

1. 1. A method of making an ultrasonic transducer device, comprising: forming a plurality of cavities in a transducer wafer bonded to a carrier substrate; contacting one or more interior surfaces of one or more of the plurality of cavities with a stabilization material; separating the transducer wafer from the carrier substrate after contacting the one or more inner surfaces with the stabilizing material; A method comprising:

2. The method of claim 1 , further comprising reducing a cross-sectional thickness of at least a portion of the transducer wafer.

3. The method of claim 2 , wherein the cross-sectional thickness of the transducer wafer is reduced to 75 micrometers or less.

4. The method of claim 2 or 3, wherein the cross-sectional thickness of the transducer wafer is reduced to 50 micrometers or less.

5. The method of any one of claims 2 to 4, wherein the step of reducing the cross-sectional thickness of at least a portion of the transducer wafer is performed prior to forming the plurality of cavities in the transducer wafer.

6. The method of any one of claims 2 to 4, wherein the step of reducing the cross-sectional thickness of at least a portion of the transducer wafer is performed after forming the plurality of cavities in the transducer wafer.

7. 7. The method of claim 2, wherein reducing the cross-sectional thickness of at least a portion of the transducer wafer is performed after contacting the one or more inner surfaces with the stabilizing material.

8. 7. The method of claim 2, wherein the step of reducing the cross-sectional thickness of at least a portion of the transducer wafer is performed prior to contacting the one or more inner surfaces with the stabilization material.

9. The method of any one of claims 1 to 8, wherein the plurality of cavities are formed in the transducer wafer using photolithography.

10. The method of any one of claims 1 to 9, wherein forming the plurality of cavities in the transducer wafer comprises etching the plurality of cavities in the transducer wafer.

11. The method of any one of claims 2 to 10, wherein reducing the cross-sectional thickness of at least a portion of the transducer wafer comprises backgrinding a surface of the transducer wafer.

12. The method of any one of claims 2 to 10, wherein reducing the cross-sectional thickness of at least a portion of the transducer wafer comprises etching a cavity sidewall of the transducer wafer.

13. The method of claim 8 or 12, wherein the etching comprises a wet etch or a plasma etch.

14. The method of any one of claims 1 to 13, wherein the transducer wafer bonded to the carrier comprises a cross-sectional thickness of 100 micrometers.

15. The method of any one of claims 1 to 14, wherein the transducer wafer bonded to the carrier comprises a cross-sectional thickness of 75 micrometers.

16. The method of claim 15 , wherein the transducer wafer bonded to the carrier comprises a cross-sectional thickness of 50 micrometers.

17. 17. The method of any one of claims 1 to 16, wherein contacting one or more inner surfaces with the stabilizing material comprises one or more of spin coating, inkjet deposition, spray deposition, physical vapor deposition (PVD), or chemical vapor deposition (CVD).

18. The method of any one of claims 1 to 17, further comprising polymerizing the stabilizing material.

19. 20. The method of claim 18, wherein the step of polymerizing the stabilizing material is performed after contacting the one or more interior surfaces with the stabilizing material.

20. 20. The method of claim 18, wherein the step of polymerizing the stabilizing material is performed simultaneously with the step of contacting the one or more interior surfaces with the stabilizing material.

21. 21. The method of claim 19 or 20, wherein polymerizing the stabilizing material comprises exposing the stabilizing material to ultraviolet (UV) light.

22. 22. The method of any one of claims 1 to 21, wherein the step of contacting one or more inner surfaces with a stabilizing material comprises filling the one or more cavities with a stabilizing material until the stabilizing material is equal to a height of one or more cavity sidewalls of the one or more cavities.

23. 22. The method of any one of claims 1 to 21, wherein the step of contacting one or more inner surfaces with a stabilizing material comprises filling the one or more cavities with a stabilizing material until the stabilizing material exceeds a height of one or more cavity sidewalls of the one or more cavities.

24. 22. The method of any one of claims 1 to 21, wherein the step of contacting one or more inner surfaces with a stabilizing material comprises filling the one or more cavities with a stabilizing material until the stabilizing material is lower than a height of one or more cavity sidewalls of the one or more cavities.

25. 25. The method of any one of claims 1 to 24, further comprising singulating the transducer wafer into one or more ultrasound transducer chips comprising the plurality of cavities and the stabilizing material, and coupling an acoustic lens coupled to one or more of the stabilizing material or transducer chips of the one or more ultrasound transducer chips.

26. The method of claim 25 , wherein the acoustic lens extends over and across each of the one or more cavities.

27. 27. The method of claim 25 or claim 26, wherein the acoustic lens is formed from the same material as the stabilizing material.

28. 27. The method of claim 25 or 26, wherein the acoustic lens is formed from a material different from the stabilizing material.

29. 29. The method of any one of claims 25 to 28, wherein the acoustic lens is formed from a lens material, and the lens material and the stabilizing material have one or more of a speed of sound, an acoustic attenuation, or an acoustic impedance that are substantially the same.

30. 30. The method of any one of claims 1 to 29, further comprising bonding one or more ultrasonic transducer chips singulated from the transducer wafer, the plurality of cavities and the stabilizing material, to an application specific integrated circuit (ASIC).

31. 31. The method of claim 30, wherein one or more ultrasonic transducer chips are coupled to the application specific integrated circuit (ASIC) by flip-chip soldering.

32. 32. The method of claim 31 , wherein the stabilization material has a thermal decomposition temperature greater than a reflow temperature of solder used to bond the one or more ultrasonic transducer chips to the application specific integrated circuit (ASIC).

33. The method of any one of claims 30 to 32, further comprising coupling the application specific integrated circuit (ASIC) to a printed circuit board (PCB).

34. 34. The method of claim 33, wherein the application specific integrated circuit (ASIC) is coupled to the printed circuit board (PCB) by wire bonding or by flip chip soldering.

35. 35. The method of claim 33 or 34, wherein the stabilization material has a thermal decomposition temperature greater than a reflow temperature of a solder used to bond the application specific integrated circuit (ASIC) to the printed circuit board (PCB).

36. The method of any one of claims 1 to 35, wherein the stabilizing material comprises silicone.

37. 37. The method of claim 36, wherein the stabilizing material comprises one or more thermal stabilizing additives selected from iron, cerium, and titanium oxide.

38. A method according to any one of the preceding claims, wherein the stabilising material has a thermal decomposition temperature above 240°C.

39. The method of any one of claims 1 to 38, wherein the ultrasonic transducer device comprises a pMUT transducer.

40. The method of any one of claims 1 to 39, wherein the ultrasonic transducer device comprises a cMUT transducer.

41. a transducer chip having a plurality of cavities; a stabilization material in contact with at least a portion of an interior surface of one or more of the plurality of cavities; an acoustic lens formed from a lens material and extending over and across the plurality of cavities; Equipped with the lens material and the stabilization material have one or more of a sound speed, an acoustic attenuation, or an acoustic impedance that are substantially the same; Ultrasonic transducer device.

42. 42. The device of claim 41, wherein at least a portion of the transducer tip has a cross-sectional thickness of no more than 50 micrometers.

43. 43. The device of claim 41 or 42, further comprising an application specific integrated circuit (ASIC) and a printed circuit board (PCB), the application specific integrated circuit (ASIC) coupled to the printed circuit board (PCB) by joints comprising solder.

44. 44. The device of claim 43, wherein the thermal decomposition temperature of the stabilizing material is greater than a reflow temperature of the solder.

45. 45. The device of claim 43 or 44, wherein the reflow temperature of the solder is 240°C.

46. A device according to any one of claims 41 to 45, wherein the stabilising material comprises one or more thermal stabilising additives selected from iron, cerium and titanium oxide.

47. A device according to any one of claims 41 to 46, wherein the stabilising material has low acoustic attenuation.

48. The device of any one of claims 41 to 47, wherein the acoustic lens is formed from a material different from the stabilizing material.

49. A device according to any one of claims 41 to 48, wherein the lens material has a thermal decomposition temperature equal to or greater than the thermal decomposition temperature of the stabilising material.

50. A device according to any one of claims 41 to 49, wherein the lens material has a thermal decomposition temperature lower than the thermal decomposition temperature of the stabilising material.

51. 51. A device according to any one of claims 41 to 50, wherein the transducer tip has a cross-sectional thickness of no more than 50 micrometers across its entire length and width.

52. The device of any one of claims 41 to 51, wherein the transducer chip comprises a pMUT transducer.

53. The device of any one of claims 41 to 51, wherein the transducer chip comprises a cMUT transducer.

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