TW202338394A - Methods and systems for fabrication of ultrasound transducer devices - Google Patents

Abstract

Described herein are methods and systems useful in the fabrication of ultrasound transducer devices. Fabrication of ultrasound transducer devices can comprise manipulation of components having extremely small cross-sectional thicknesses, which can increase the risk of damage to the components. For example, inadvertent application of forces sufficient to damage such components is a significant risk during fabrication steps. As described herein, the risk of damage to an ultrasound transducer device component having a small cross-sectional thickness, such as an ultrasound microelectromechanical system (MEMS) wafer, can be reduced by partially or completely coating or filling all or a portion of the component with a stabilizing material, for example, prior to subjecting the component to forces associated with manipulation of the component during the fabrication process.

Description

Methods and systems for manufacturing ultrasonic sensor devices

Sensitive components of ultrasonic sensors can be damaged during manufacturing using conventional methods and systems, for example due to inadvertent bending of the components during the manufacturing process. In some cases, sufficient array diaphragms of an ultrasonic sensor device can be damaged during manufacturing, rendering the device unreliable or unusable. Repair of sensor components damaged during manufacturing can be time-consuming and expensive. In some cases, sensor array components damaged during manufacturing cannot be repaired and the units must be discarded reducing manufacturing yield. In some cases, it cannot be determined whether ultrasonic device components have been damaged during manufacturing to the extent that the ultrasonic sensor device must be discarded until the device is fully assembled and tested, thereby increasing unit costs. Therefore, in many cases, ultrasonic device manufacturers using existing ultrasonic device manufacturing methods and systems must bear the lost unit costs of unusable or unreliable devices that have components that are damaged during manufacturing. Therefore, it is desirable to improve systems and methods for fabricating sensor devices.

Fabrication of the ultrasonic sensor device may involve manipulation of fragile device components (eg one or more of the ultrasonic sensor device components are at risk of breakage or breakage, eg due to the application of mechanical force to the component(s)). For example, a microelectromechanical system (MEMS) component used to generate and/or receive ultrasonic energy during operation of an ultrasonic sensor device may have one or more cross-sectional dimensions that render the component susceptible to damage due to forces applied to the component ( such as cross-sectional thickness). Existing techniques for ultrasonic sensor device fabrication may involve applying forces to such ultrasonic sensor device components (e.g., applying components to a substrate during fabrication, releasing components from a temporary substrate, and/or translating components from one position to (during another position), which may increase the risk of component damage (such as breakage or breakage). Indeed, damage to components during the manufacture of an ultrasonic sensor device can affect the functionality of the ultrasonic sensor device and can result in substantial and expensive total losses in product production.

As described herein, the risk of component damage during manufacturing can be reduced by mechanically stabilizing the component during manufacturing. For example, a component may be mechanically stabilized by adding a stabilizing material to the component (eg, by partially or completely coating or filling all or part of the component with the stabilizing material). In some cases, manufacturing steps involving physical manipulation of the component, such as the component to a structural support (eg, a carrier substrate), releasing the component from the structural support, and/or attaching the component to one or more additional device components, may be preceded by Stabilizing materials are added to components, for example, to reduce the risk of damage, such as partial breakage or breakage of the component.

In various aspects, a method of fabricating an ultrasonic sensor device includes: forming a plurality of cavities in a sensor wafer coupled to a carrier substrate; causing one or more of the plurality of cavities to The inner surface is in contact with the stabilizing material; and the sensor wafer is decoupled from the carrier substrate after contacting the one or more inner surfaces with the stabilizing material. In some cases, the method includes reducing a cross-sectional thickness of at least a portion of the sensor wafer. In some cases, the cross-sectional thickness of the sensor wafer is reduced to no more than 75 microns. In some cases, the cross-sectional thickness of the sensor wafer is reduced to no more than 50 microns. In some cases, reducing the cross-sectional thickness of at least a portion of the sensor wafer is performed before causing the cavities to be formed in the sensor wafer. In some cases, reducing the cross-sectional thickness of at least a portion of the sensor wafer is performed after forming the cavities in the sensor wafer. In some cases, reducing the cross-sectional thickness of at least a portion of the sensor wafer is performed after contacting the one or more inner surfaces with the stabilizing material. In some cases, reducing the cross-sectional thickness of at least a portion of the sensor wafer is performed before contacting the one or more inner surfaces with the stabilizing material. In some cases, the plurality of cavities are formed in the sensor wafer using photolithography. In some cases, causing the plurality of cavities to be formed in the sensor wafer includes etching the plurality of cavities in the sensor wafer. In some cases, reducing the cross-sectional thickness of at least a portion of the sensor wafer includes back grinding a surface of the sensor wafer. In some cases, reducing the cross-sectional thickness of at least a portion of the sensor wafer includes etching cavity sidewalls of the sensor wafer. In some cases, the etching includes wet etching or plasma etching. In some cases, the sensor wafer coupled to the carrier includes a cross-sectional thickness of 100 microns. In some cases, the sensor wafer coupled to the carrier includes a cross-sectional thickness of 75 microns. In some cases, the sensor wafer coupled to the carrier includes a cross-sectional thickness of 50 microns. 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 interior surfaces with the stabilizing material includes filling the one or more cavities with the stabilizing material until the stabilizing material is flush with a height of one or more cavity sidewalls of the one or more cavities. In some cases, contacting the one or more interior 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 interior surfaces with the stabilizing material includes filling the one or more cavities with the stabilizing material until the stabilizing material is below the height of one or more cavity sidewalls of the one or more cavities. In some cases, the method further includes: singulating the sensor wafer into one or more ultrasonic sensor wafers including the plurality of cavities and the stabilizing material; and coupling an acoustic lens to the stabilizing material. or one or more of the one or more ultrasonic sensor 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 different material than the stabilizing material. In some cases, the acoustic lens is formed from a lens material, and wherein the lens material and the stabilizing material have substantially the same one or more of acoustic velocity, acoustic attenuation, or acoustic impedance. In some cases, the method further includes coupling one or more ultrasonic sensor wafers singulated from the sensor wafer including the plurality of cavities and the stabilizing material to an application specific integrated circuit (ASIC). In some cases, one or more ultrasonic sensor dies are coupled to the ASIC via flip-chip soldering. In some cases, the stabilizing material has a decomposition temperature that is higher than the reflow temperature of the solder used to couple the one or more ultrasonic sensor dies 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 coupled to the PCB by wire bonding or by flip chip soldering. In some cases, the stabilizing material has a decomposition temperature that is higher than the reflow temperature of the solder used to couple the ASIC to the PCB. In some cases, the stabilizing material includes polysiloxane. In some cases, the stabilizing material includes one or more thermal stabilizer additives selected from iron, cerium, and titanium oxide. In some cases, the stable material has a decomposition temperature greater than 240°C. In some cases, the ultrasonic sensor device includes a pMUT sensor. In some cases, the ultrasonic sensor device includes a cMUT sensor.

In various aspects, an ultrasonic sensor device includes: a sensor wafer including a plurality of cavities; a stabilizing material in contact with at least a portion of an interior surface of one or more of the plurality of cavities; and an acoustic lens in the plurality of cavities. Extending over and across the plurality of cavities is a lens material, wherein the lens material and the stabilizing material have substantially the same one or more of sound velocity, sound attenuation, or acoustic impedance. In some cases, at least a portion of the sensor wafer has a cross-sectional thickness of up to 50 microns. In some cases, the device further includes an application specific integrated circuit (ASIC) and a printed circuit board (PCB), wherein the ASIC is coupled to the PCB by a junction including solder. In some cases, the decomposition temperature of the stabilizing material is greater than the 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 stabilizer additives selected from iron, cerium, and titanium oxide. In some cases, the stabilizing material has acoustic attenuation. In some cases, the acoustic lens is formed from a different material than the stabilizing material. In some cases, the lens material has a decomposition temperature equal to or greater than the decomposition temperature of the stabilizing material. In some cases, the lens material has a decomposition temperature that is less than the decomposition temperature of the stabilizing material. In some cases, the sensor wafer has a cross-sectional thickness of up to 50 microns across the entire length and width of the sensor wafer. In some cases, the ultrasonic sensor device includes a pMUT sensor. In some cases, the ultrasonic sensor device includes a cMUT sensor.

Described herein are methods, systems, and devices for reducing the risk of damage to one or more components of an ultrasonic sensor device during device fabrication. The ultrasonic sensor device may include one or more components that, for example, have a diameter measuring 50 micrometers (μm) when applying forces (such as normal and/or shear forces) to areas where there is a risk of damage. or smaller cross-sectional dimensions) one or more components are susceptible to damage (e.g., via breakage or breakage). As described herein, the risk of damage to one or more components of an ultrasonic sensor device can be reduced by mechanically stabilizing the one or more components (or portions thereof) during manufacturing. For example, a MEMS wafer that may exhibit a thickness that may render the wafer susceptible to damage during ultrasonic sensor device fabrication (e.g., 50 microns or less) may be available with a material that can mechanically stabilize the MEMS wafer during processing (e.g., a stabilizing material) Partially or completely coated or filled.

In some cases, the risk of damage to components of an ultrasonic sensor device may be addressed by prior to fabrication steps involving releasing the components from the solid support and/or before applying substantial mechanical forces to the wafer (e.g., prior to manipulating the wafer). ) is reduced by partially or completely coating or filling a component with a material capable of mechanically stabilizing the component, as described herein. In some cases, a material can mechanically stabilize a component (or portion thereof) if it can be used to physically resist bending of the component (eg, 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 the ultrasonic sensor device during manufacturing may be based on its material properties such as melting point, cure time, desired cure conditions, ultrasonic transmission rate, viscosity, and/or elastic modulus) to select one or more. In some cases, the material used to form the lens of the ultrasonic sensor device (which may have properties that allow the material to be coated on all or part of the component or fused into one or more cavities of the component) may be used to mechanically stabilize during fabrication One or more components of an ultrasonic sensor device. The use of materials with these properties to mechanically stabilize components of an ultrasonic sensor device (such as MEMS wafers or portions thereof) can reduce the risk of damage to the components while avoiding significant adverse effects on ultrasonic transmission during operation of the device.

In some cases, fabrication of ultrasonic sensor devices may include making components of the device thinner relative to the cross-sectional height, width, and/or length of the components (eg, by back grinding and/or etching). In some cases, components including ultrasonic sensor devices with thin cross-sectional dimensions (e.g., having a cross-sectional height, length, and/or width less than or equal to 50 micrometers (μm)) may, for example, apply forces during processing. Vulnerable to damage when attached to the component (eg, when the component is released from the carrier substrate, attached to one or more additional ultrasound device components, attached to one or more additional carrier substrates). Overview

The methods and systems described herein may include one or more ultrasonic sensor devices 100 (eg, ultrasonic sensors). The ultrasonic sensor device 100 may be used, for example, to transmit ultrasonic energy to and/or receive ultrasonic energy from a target location on a target material to form an image of the target location on the target material. In some cases, ultrasonic sensors may be used, for example, to image biological tissue to determine physiological conditions of the biological tissue or a subject including the biological tissue. The ultrasonic sensor devices described herein may be portable (eg, handheld). In some cases, the size of the ultrasonic sensor device can be reduced by reducing one or more cross-sectional dimensions (eg, cross-sectional thickness) of one or more of the components that make up the ultrasonic sensor device. In some cases, reducing the size of the ultrasonic sensor device (eg, by reducing the cross-sectional thickness of one or more ultrasonic sensor device components) may make the ultrasonic sensor device easier to maneuver. In some cases, increasing the maneuverability of the ultrasound sensor device may make the ultrasound sensor device more portable and/or easier to use during imaging procedures.

Ultrasonic sensor device 100 may include an ultrasonic sensor wafer 102 (eg, as shown in Figures 1A and 1B). In some cases, ultrasonic sensor wafer 102 may include microelectromechanical systems (MEMS) sensors. In some cases, the MEMS sensor may be a piezoelectric micromachined ultrasonic sensor (pMUT). In some cases, the MEMS sensor may be a capacitive micromachined ultrasonic sensor (cMUT). In some cases, the cross-sectional thickness 130 of the ultrasonic sensor wafer 102 or portions thereof can significantly affect the likelihood (eg, risk) of damaging the ultrasonic sensor wafer or portions thereof (eg, a MEMS sensor or portions thereof) during manufacturing. In many cases, preventing damage to the ultrasonic sensor wafer 102 during manufacturing is important to preserve the functionality (eg, including accuracy and/or reliability) of the ultrasonic sensor device 100 including the ultrasonic sensor wafer 102 .

As shown in FIGS. 2A and 2B , a method of manufacturing an ultrasonic sensor device 100 may include providing an ultrasonic sensor wafer 102 (eg, having an initial cross-sectional thickness 130). In some cases, ultrasonic sensor wafer 102 may include a metal back layer 104 . In some cases, methods of fabricating an ultrasonic sensor device may include, for example, coupling ultrasonic wafer 102 to solid support 108 (eg, carrier substrate 108) using adhesive 106 (eg, steps of FIGS. 2A and 2B 902). In some cases, the adhesive used to couple the ultrasonic sensor wafer 102 to the solid support 108 may be a releasable adhesive. The use of a debondable adhesive may facilitate release of the ultrasonic sensor wafer 102 from the solid support 108 during later stages of the manufacturing process. In some cases, methods of fabricating ultrasonic sensor device 100 may include providing ultrasonic sensor wafer 102 (e.g., having Initial cross-section thickness 130). The solid support (eg, carrier substrate) may include, for example, glass or quartz. In some cases, the ultrasonic sensor wafer may include a silicon layer coupled to a metal backing layer. In some cases, the metal backing layer may be directly coupled to the solid support (eg, between the silicon layer and the solid support of the ultrasonic sensor wafer). In some cases, the ultrasonic sensor wafer or portions thereof (eg, metal backing) may be coupled to the solid support via an adhesive (eg, a releasable adhesive).

Methods of fabricating the ultrasonic sensor device 100 may include reducing the cross-sectional thickness of the ultrasonic sensor wafer 102 or a portion thereof (eg, from an initial cross-sectional thickness 130 to a reduced cross-sectional thickness 131 ). For example, a method of fabricating the ultrasonic sensor device 100 may include reducing the thickness of the silicon layer of the ultrasonic sensor wafer 102 , such as from an initial cross-sectional thickness 130 to a reduced cross-sectional thickness 131 . Reducing the cross-sectional thickness of the ultrasonic sensor wafer 102 may include back grinding the ultrasonic sensor wafer 102 or portions thereof (eg, the silicon layer of the ultrasonic sensor wafer 102). In some cases, reducing the cross-sectional thickness of the ultrasonic sensor wafer 102 may include using photolithography. In some cases, reducing the cross-sectional thickness of ultrasound sensor wafer 102 may include etching ultrasound sensor wafer 102 or portions thereof (eg, using wet etching or plasma etching techniques). In some cases, reducing the cross-sectional thickness of the ultrasonic sensor wafer may improve the functionality of the ultrasonic sensor device (e.g., the quality and/or reliability (e.g., reproducibility) of generating and/or detecting ultrasonic energy waves) . In some cases, reducing the cross-sectional thickness of the ultrasonic sensor wafer 102 may assist in reducing the overall size of the ultrasonic sensor device 100.

In some cases, a method of fabricating the ultrasonic sensor device 100 may include reducing the cross-sectional thickness of the ultrasonic sensor wafer 102 from an initial cross-sectional thickness 130 to a reduced cross-sectional thickness 131 (e.g., as shown in FIGS. 2A and 131 ). shown in step 904 of 2B and step 702 of Figure 4). In some cases, reducing the cross-sectional thickness may include reducing the cross-sectional thickness across the entire width and length of the ultrasonic sensor wafer 102 (eg, as where back grinding is used to reduce the ultrasonic sensor wafer 102 prior to cavity formation. Some cases of cross-sectional thickness, for example, as shown in Figures 2A and 2B). In some cases, reducing the cross-sectional thickness of the ultrasonic sensor wafer 102 may include reducing the cross-sectional thickness of one or more portions of the ultrasonic sensor wafer 102 (e.g., where formed in the ultrasonic sensor wafer 102 The cavity then reduces the cross-sectional thickness of the cavity sidewalls, for example, as shown in Figure 4). In some cases, the ultrasonic sensor wafer may include the following cross-sectional thicknesses: from 20 microns (μm) to 100 microns, from 20 microns to 75 microns, from 30 microns to 75 microns, from 40 microns to 75 microns, from 50 Micron to 75 micron or from 40 micron to 50 micron. In some cases, a method of fabricating the ultrasonic sensor device 100 may include providing the ultrasonic sensor wafer 102 (eg, coupled to the carrier substrate 108) with an initial cross-sectional thickness of: greater than 100 microns, at least 100 microns, at least 75 microns, At least 50 microns, at least 40 microns, at least 30 microns or at least 20 microns. In some cases, methods of fabricating ultrasonic sensor device 100 may include reducing the cross-sectional thickness of ultrasonic sensor wafer 102 to a cross-sectional thickness of 1 micron to 100 microns (eg, reduced cross-sectional thickness). In some cases, methods of fabricating ultrasonic sensor device 100 may include reducing the cross-sectional thickness of ultrasonic sensor wafer 102 to a cross-sectional thickness of 1 micron to 50 microns (eg, reduced cross-sectional thickness). In some cases, reducing the cross-sectional thickness of the ultrasonic sensor wafer 102 may include reducing the cross-sectional thickness to a value from about 1 micron to about 120 microns. In some cases, reducing the cross-sectional thickness of the ultrasonic sensor wafer 102 may include reducing the cross-sectional thickness to from about 1 micron to about 20 microns, from about 1 micron to about 30 microns, from about 1 micron to about 30 microns. About 40 microns, about 1 micron to about 50 microns, about 1 micron to about 60 microns, about 1 micron to about 75 microns, about 1 micron to about 85 microns, about 1 micron to about 100 microns, about 1 micron to about 110 Micron, about 1 micron to about 120 micron, about 20 micron to about 30 micron, about 20 micron to about 40 micron, about 20 micron to about 50 micron, about 20 micron to about 60 micron, about 20 micron to about 75 micron, About 20 microns to about 85 microns, about 20 microns to about 100 microns, about 20 microns to about 110 microns, about 20 microns to about 120 microns, about 30 microns to about 40 microns, about 30 microns to about 50 microns, about 30 Micron to about 60 micron, about 30 micron to about 75 micron, about 30 micron to about 85 micron, about 30 micron to about 100 micron, about 30 micron to about 110 micron, about 30 micron to about 120 micron, about 40 micron to About 50 microns, about 40 microns to about 60 microns, about 40 microns to about 75 microns, about 40 microns to about 85 microns, about 40 microns to about 100 microns, about 40 microns to about 110 microns, about 40 microns to about 120 microns Micron, about 50 micron to about 60 micron, about 50 micron to about 75 micron, about 50 micron to about 85 micron, about 50 micron to about 100 micron, about 50 micron to about 110 micron, about 50 micron to about 120 micron, About 60 microns to about 75 microns, about 60 microns to about 85 microns, about 60 microns to about 100 microns, about 60 microns to about 110 microns, about 60 microns to about 120 microns, about 75 microns to about 85 microns microns, about 75 microns to about 100 microns, about 75 microns to about 110 microns, about 75 microns to about 120 microns, about 85 microns to about 100 microns, about 85 microns to about 110 microns, about 85 microns to about 120 microns, about 100 microns to about 110 microns, from about 100 microns to about 120 microns, or from about 110 microns to about 120 microns. In some cases, reducing the cross-sectional thickness of the ultrasonic sensor wafer 102 may include reducing the cross-sectional thickness to a value from: about 1 micron, about 20 microns, about 30 microns, about 40 microns, about 50 microns. , about 60 microns, about 75 microns, about 85 microns, about 100 microns, about 110 microns or about 120 microns. In some cases, reducing the cross-sectional thickness of the ultrasonic sensor wafer 102 may include reducing the cross-sectional thickness to a value from: at least about 1 micron, at least about 20 microns, at least about 30 microns, at least about 40 microns. , at least about 50 microns, at least about 60 microns, at least about 75 microns, at least about 85 microns, at least about 100 microns, at least about 110 microns, or at least about 120 microns. In some cases, reducing the cross-sectional thickness of the ultrasonic sensor wafer 102 may include reducing the cross-sectional thickness to a value from: up to about 20 microns, up to about 30 microns, up to about 40 microns, up to about 50 microns. , up to about 60 microns, up to about 75 microns, up to about 85 microns, up to about 100 microns, up to about 110 microns, or up to about 120 microns. Methods of fabricating ultrasonic sensor device 100 may have the following tolerances relative to the cross-sectional thickness to which ultrasonic sensor wafer 102 may be reduced: ±10 microns, ±5 microns, ±1 micron, or any two of these values. Values in between (eg, tolerances from 5 microns to 10 microns, from 1 micron to 10 microns, or from 1 micron to 5 microns). In some cases, reducing the cross-sectional thickness of the ultrasonic sensor wafer 102 may increase the risk of damage to the ultrasonic sensor wafer 102 (e.g., by reducing its ability to resist torque, torsion, or bending forces, force may damage parts of the sensor wafer).

In some cases, methods of fabricating ultrasonic sensor devices may include providing an ultrasonic sensor wafer including one or more cavities 110 . The cavity 110 in the ultrasonic sensor wafer 102 may assist in the transmission of ultrasonic energy to and/or from the ultrasonic sensor diaphragm (eg, diaphragm) of the ultrasonic sensor device 100 . For example, the lumen of cavity 110 (which may be partially or completely filled with a material having low acoustic attenuation, such as stabilizing material 101 ) may serve as the distal end through which ultrasonic energy enters or exits ultrasonic sensor device 100 (e.g., via acoustic lens 114 ) conduit or path. In many cases, one or more such paths are provided (e.g., in the form of one or more cavities 110 ), which may each be spatially aligned with and optionally coupled to a pMUT or cMUT sensor element in the ultrasonic sensor device 100 to the pMUT or cMUT sensor element) may allow or improve the generation, detection and/or transmission of ultrasonic energy by the sensor element of the ultrasonic sensor device 100 (eg, compared to the use of a wafer that does not include a cavity). (For example, a plurality of cavities (eg, form an array). Cavity 110 of ultrasonic sensor wafer 102 may include an inner lumen. The cavity 110 of the ultrasonic sensor wafer 102 may include a plurality of interior surfaces. For example, the cavity 110 of the ultrasonic sensor wafer 102 may include an inner surface of the bottom of the cavity 110 and one or more inner surfaces of the cavity sidewalls. In some cases, the bottom wall of the ultrasonic sensor wafer cavity 110 may be actuated (e.g., by one or more piezoelectric actuators, which may be driven by an ASIC and/or computer system) to (e.g., ) generates ultrasonic energy signals for transmission to target substances.

In some cases, the process of fabricating the ultrasonic sensor device 100 may include forming one or more cavities 110 in the ultrasonic sensor wafer 102 (eg, in step 906 of FIGS. 2A and 2B and step 652 of FIG. 3 shown). In some cases, a plurality of cavities may be formed in the ultrasonic sensor wafer 102 . In some cases, a plurality of cavities may be formed in the ultrasonic sensor wafer 102 in an array pattern (eg, where the array corresponds to an array of the ASIC 116 to which the ultrasonic sensor wafer 102 will be coupled during processing). In some cases, one or more cavities 110 may be formed in the ultrasonic sensor wafer 102 or a portion thereof (eg, a silicon layer of the ultrasonic sensor wafer 102 ) using photolithography. In some cases, photolithography may include the use of masks or patterns to prevent undesired areas from being exposed to photolithography energy. In some cases, one or more cavities 110 may be formed in the ultrasonic sensor wafer 102 (e.g., a silicon layer of the ultrasonic sensor wafer 102 ), such as by etching the ultrasonic sensor wafer 102 using wet etching or plasma etching. in wafer 102.

In some cases, reducing the cross-sectional thickness (eg, height) of the ultrasonic sensor wafer or its cavity sidewalls can help reduce the overall size of the ultrasonic sensor device and/or improve the performance of the MEMS sensor array. In some cases, reducing the cross-sectional thickness of the ultrasonic sensor wafer (e.g., during fabrication) may increase the risk of damage (e.g., fracture or breakage) of the ultrasonic sensor wafer (e.g., where the sensor wafer is not (e.g., ) during the steps of the process that are mechanically supported by a carrier substrate). In some cases, reducing the cross-sectional thickness of the ultrasonic sensor wafer 102 may increase the risk of breakage or breakage of the ultrasonic sensor wafer or portions thereof during fabrication of the ultrasonic sensor device 100 (e.g., during wafer processing) (e.g., during wafer processing). The possibility of the sensor diaphragm forming the bottom wall of the sensor wafer cavity). For example, reducing the cross-sectional thickness of an ultrasonic sensor wafer (e.g., from an initial cross-sectional thickness of 100 microns or greater to, for example, 50 micrometers (μm) or less) can cause the wafer to become more flexible, It can increase the likelihood that the ultrasonic sensor wafer, or portions thereof (such as the sensor diaphragm that forms the bottom wall of the sensor wafer cavity) will fracture or break even when subjected to moderate forces, such as those associated with ultrasonic sensor device manufacturing. Such as debonding the sensor wafer from the carrier substrate and/or physically transferring the ultrasonic sensor wafer to a different substrate (eg, ASIC). In some cases, the risk of damaging the ultrasonic sensor wafer 102 during manufacturing may depend on the ratio of the cross-sectional thickness of the wafer to the width or length of the wafer. In some cases, the first ultrasonic sensor wafer 102 having a greater width and/or length and the same cross-sectional thickness than the second ultrasonic sensor wafer 102 may have greater damage during fabrication than the second wafer. risk. In some cases, the first ultrasonic sensor wafer 102 having the same length and width dimensions and a small cross-sectional thickness may have a greater risk of damage during manufacturing than the second ultrasonic sensor wafer 102 . In some cases, ultrasonic sensor wafers 102 that include a thickness of 300 microns or less and a width and/or length of 6 inches (or greater) are produced during fabrication (e.g., during unsupported handling or manipulation of the wafer). and without the addition of stabilizing materials) may pose a significant risk of damage to the wafer, including the manufacture of ultrasonic sensor wafers 102 with a thickness of 400 microns or less and a width and/or length of 8 inches (or greater). There can also be a significant risk of damage to the wafer during unsupported handling or manipulation of the wafer without the addition of stabilizing materials.

As described herein, the risk of damaging the ultrasonic sensor wafer 102 (eg, during steps of the process where the ultrasonic sensor wafer 102 is not mechanically supported) can be reduced by adding stabilizing material 101 to the ultrasonic sensor wafer. 102 in whole or in part to reduce. For example, the stabilizing material 101 may be used to coat or fill all or part of the surface of an ultrasonic sensor wafer with a small cross-sectional thickness (eg, up to 50 microns) to reduce the risk of damaging the wafer 102 during manufacturing. In some cases, stabilizing material may be added to one or more cavities of the ultrasonic sensor wafer to, for example, mechanically stabilize the wafer 102 . For example, a stabilizing material may be used to coat the bottom surface of the ultrasonic sensor wafer cavity (e.g., before the wafer is released from the carrier substrate) to increase the mechanical stability of the wafer 102 , which may help resist forces that may be applied to the wafer 102 Force (such as torque, torsion or bending force). Adding stabilizing materials to the cavity or portions thereof (eg, interior surfaces of the cavity 110 , such as the interior surfaces of the cavity bottom 112 ) may be particularly beneficial in reducing the risk of damage to the ultrasonic sensor wafer 102 as compared to not reducing the cross-sectional thickness Portions of a silicon ultrasonic sensor wafer that have reduced cross-sectional thickness, such as the bottom wall of a cavity formed during a manufacturing process, may have higher Risk of damage (such as breakage or breakage).

In some cases, one or more surfaces of the ultrasonic sensor wafer 102 may, for example, be located on the ultrasonic sensor wafer 102 (which may be 50 microns or less, 40 microns or less, 30 microns or less, or A cross-sectional thickness of 20 microns or less) is contacted with (e.g., partially or fully coated with the stabilizing material 101) prior to decoupling from the solid support 108 (e.g., step 908 and FIG. 2B of FIGS. 2A and 2B shown in step 704 of 4). For example, a method of fabricating ultrasonic sensor device 100 may include contacting one or more interior surfaces of cavities 110 (eg, cavities 110 ) of ultrasonic sensor wafer 102 with stabilizing material 101 (e.g., before contacting wafer 102 with (before solid support 108 is decoupled). In some cases, contacting one or more interior surfaces (eg, of cavity 110) with the stabilizing material includes filling the one or more cavities with the stabilizing material until the stabilizing material contacts one or more of the cavity sidewalls of the one or more cavities. Flush height. In some cases, contacting one or more interior surfaces (eg, of cavity 110) with the stabilizing material includes filling the one or more cavities with the stabilizing material until the stabilizing material exceeds one or more of the cavity sidewalls. high. In some cases, contacting one or more interior surfaces (eg, of cavity 110 ) with the stabilizing material includes filling the one or more cavities with the stabilizing material until the stabilizing material is below one or more of the cavity sidewalls the height. In some cases, contacting one or more surfaces of the ultrasonic sensor wafer 102 with the stabilizing material 101 may reduce the risk of damage to the ultrasonic sensor wafer 102 (e.g., caused by releasing the wafer 102 from the solid support 108 (caused by forces applied to wafer 102 during the manufacturing steps). In some cases, the interior surface of the bottom wall of the cavity 110 of the ultrasonic sensor wafer 102 may be completely coated with the stabilizing material 101 . In some cases, the cavity 110 of the ultrasonic sensor wafer 102 may be partially filled with the stabilizing material 101 (e.g., such that the stabilizing material 101 covers the entire interior surface of the bottom wall of the ultrasonic sensor wafer 102 but does not contact one or more of the cavity sidewalls) 111, for example, as shown in Figures 2A and 2B). In some cases, the cavity 110 of the ultrasonic sensor wafer 102 may be completely filled with the stabilizing material 101 (e.g., such that the stabilizing material 101 covers the entire interior surface of the bottom wall of the ultrasonic sensor wafer 102 and fills the cavity up to the cavity sidewalls 111 (e.g., such that the stabilizing material 101 contacts the entire height of one or more of the cavity side walls 111 of the cavity 110). In some cases, the cavity 110 of the ultrasonic sensor wafer 102 may be overfilled with the stabilizing material 101 (e.g., such that the stabilizing material 101 completely fills the cavity 110 and covers the top of one or more cavity sidewalls 111 of the ultrasonic sensor wafer 102, For example, as shown in Figure 3). For example, before one or more cavities 110 (eg, an array of cavities 110) are formed in the ultrasonic sensor wafer 102 (eg, by photolithography using a photolithographic pattern), ultrasonic sensors coupled to the solid support 108 The sonic sensor wafer 102 may have its cross-sectional thickness reduced (eg, by back grinding) to, for example, a cross-sectional thickness of 50 microns or less, for example, as shown in FIG. 3 . In some cases, the stabilizing material 101 may be added to partially or completely fill one or more of the cavities 110 after rendering the cross-sectional thickness of the one or more cavity sidewalls 111 to a reduced thickness (eg, 50 microns or less). , for example, as shown in Figure 3. In some cases, additional stabilizing material 101 (eg, having a high decomposition temperature) may be added beyond the thickness of cavity sidewalls 111 (eg, as shown in Figure 3) to, for example, form a lens. In some cases, the ultrasonic sensor wafer 102 with added stabilizing material 101 can be decoupled from the solid support 108 , and in some cases, the ultrasonic sensor wafer 102 can be singulated (e.g., by using a saw or laser cutting or segmenting). In some cases, one or more of the cavity sidewalls 111 of the cavity 110 partially or completely filled with the stabilizing material 101 may have a reduced cross-sectional thickness after the stabilizing material 101 is added (and, for example, subsequently cured to allow setting). For example, as shown in step 702 of Figure 4. For example, an ultrasonic sensor crystal coupled to solid support 108 may be formed before etching one or more of the cavity sidewalls 111 to reduce the cross-sectional thickness of the cavity sidewalls 111 (eg, to a cross-sectional thickness of 50 microns or less). One or more cavities 110 in circle 102 may be partially (or completely) filled with stabilizing material 101 . In some cases, additional stabilizing material 101 (e.g., having a high decomposition temperature) may be added to completely fill one or more cavities 110 or extend beyond one or more cavity sidewalls 111 (e.g., to form a lens, e.g., as shown in Figure 2B and shown in Figure 4). In some cases, the stabilizing material 101 can help reduce the risk of damage to the ultrasonic sensor wafer 102 when added to one or more surfaces of the ultrasonic sensor wafer 102 until the stabilizing material 101 has a cross-sectional thickness of: less than 5 microns, At least 5 microns, at least 10 microns, at least 20 microns, at least 30 microns, at least 40 microns, at least 50 microns, over 50 microns, from 5 microns to 50 microns, from 20 microns to 50 microns, from 20 microns to 40 microns or from 20 microns to 30 microns (eg, where the cross-sectional thickness is measured after solidification of the stabilizing material).

In some cases, ultrasonically contacting one or more surfaces (eg, one or more interior surfaces of cavity 110 ) with stabilizing material 101 may include spin coating stabilizing material 101 onto the one or more surfaces. In some cases, spin coating of stabilizing material 101 may be performed under vacuum conditions, for example, to reduce or eliminate bubble formation. In some cases, ultrasonically contacting one or more surfaces (eg, one or more interior surfaces of cavity 110 ) with stabilizing material 101 may include inkjet deposition of stabilizing material 101 onto the one or more surfaces. In some cases, inkjet deposition may be performed under vacuum conditions to, for example, reduce or eliminate bubble formation. In some cases, ultrasonically contacting one or more surfaces (eg, one or more interior surfaces of cavity 110 ) with stabilizing material 101 may include spray depositing stabilizing material 101 onto the one or more surfaces. In some cases, ultrasonically contacting one or more surfaces (eg, one or more interior surfaces of cavity 110 ) with stabilizing material 101 may include chemical vapor deposition (CVD) of stabilizing material 101 onto the one or more surfaces. superior. In some cases, ultrasonically contacting one or more surfaces (eg, one or more interior surfaces of cavity 110 ) with stabilizing material 101 may include physical vapor deposition (PVD) of stabilizing material 101 onto the one or more surfaces. superior. In some cases, a mask or pattern may be used to ensure that the stabilizing material 101 is deposited on a desired surface and/or to ensure that the stabilizing material 101 is not deposited on an undesired surface. In some cases, the stabilizing material 101 may be allowed to solidify after it is added to one or more surfaces of the ultrasonic sensor wafer 102 . In some cases, the stabilizing material 101 may be actively caused to solidify (eg, by curing, eg, using exposure to ultraviolet (UV) light) after the stabilizing material 101 is added to one or more surfaces of the ultrasonic sensor wafer 102 . Ensuring that the stabilizing material 101 does not contain air bubbles after deposition (e.g., by depositing the stabilizing material 101 under vacuum and/or using techniques such as spray deposition, CVD, or PVD) ensures that the acoustic properties of the deposited stabilizing material 101 do not negatively impact the ultrasonic Sonic energy is transmitted through the stabilizing material 101 during operation of the ultrasonic sensor device 100 .

In some cases, additional stabilizing material 101 may be added to ultrasonic sensor wafer 102 to cover one or more surfaces of ultrasonic sensor wafer 102 and/or to solidify after initial deposition of stabilizing material 101 . part, for example, as shown in Figure 4. In some cases, acoustic lens 114 may be formed from the same material as stabilizing material 101 . For example, acoustic lens 114 may be formed from stabilizing material 101 added to one or more surfaces of ultrasonic sensor wafer 102 and/or portions of stabilizing material 101 that solidify after initial deposition of stabilizing material 101 . In some cases, the acoustic lens 114 may be coupled to an ultrasonic sensor wafer singulated from an ultrasonic sensor wafer (e.g., including a plurality of cavities) and/or (e.g., singulated from an ultrasonic sensor wafer including a plurality of cavities). One or more of the stabilizing materials 101 of the ultrasonic sensor chip of each cavity. In some cases, the acoustic lens 114 may extend across the ultrasonic sensor wafer or one or more cavities of the ultrasonic sensor wafer (eg, across and over the one or more cavities).

In some cases, after bringing the ultrasonic sensor wafer 102 into contact with the stabilizing material 101, the ultrasonic sensor wafer 102 may be decoupled from the solid support 108 (eg, step 910 of Figures 2A and 2B and Figure 3 shown in step 654). In some cases, decoupling the ultrasonic sensor wafer 102 from the solid support 108 may include debonding the releasable adhesive. In some cases, the ultrasonic sensor wafer 102 may be singulated using a saw or by laser singulation (e.g., singulated into one or more ultrasonic sensor wafers, e.g., including a plurality of cavities formed in the wafer). and one or more ultrasonic sensor chips of stabilizing material).

Methods of manufacturing the ultrasonic sensor device 100 may include assembling the ultrasonic sensor wafer 102 including the stabilizing material 101 and one or more additional components of the ultrasonic sensor device 100 (e.g., in step 912 of FIG. 2A and step 914 of FIG. 2B shown). The ultrasonic sensor wafer 102 (or a portion thereof, such as an ultrasonic sensor wafer, which may be a singulated portion of the ultrasonic sensor wafer) may be coupled to an application specific circuit (ASIC) 116 . As shown in FIG. 2A , ultrasonic sensor wafer 102 may be coupled to the conductors of metal layer 117 of ASIC 116 . In some cases, metal layer 117 of ASIC 116 may be coupled to conductors of metal layer 121 of PCB 120 by wires 126 , which may be soldered to each of the metal layers. In some cases, non-conductive die attach material 118 may be disposed between ASIC 116 and PCB 120, as shown in Figure 2A. In some cases, ultrasonic sensor wafer 102 (or portions thereof, such as ultrasonic sensor wafers) may be coupled to ASIC 116 via flip-chip soldering. As shown in FIG. 2B , ultrasonic sensor wafer 102 may be coupled to conductors of metal layer 117 of ASIC 116 , which may include through silicon through silicon (TSV) connections 122 . In some cases, TSV connection 122 may be coupled to metal layer 121 of PCB 120 through a junction such as flip-chip solder 124 (eg, which may be located in non-conductive adhesive layer 119 disposed between the ASIC and the PCB). conductor, as shown in Figure 2B.

FIG. 5A shows a flow diagram of a method 500 of manufacturing an ultrasonic sensor device 100 including a stabilizing material 101 . Method 500 may include step 502 of providing a first component (eg, ultrasonic sensor wafer 102 ) coupled to solid support 108 . Next, one or more features (eg, including one or more cavities 110 ) may be formed on the first component using photolithography, as shown in step 504 . Stabilizing material 101 may be applied to one or more surfaces of the first component, as shown in step 506 . As shown in step 508, the first component may be released (eg, decoupled) from the solid support 108. Method 500 may also include coupling the first component to a second component (eg, an ASIC) after applying the stabilizing material to the first component and decoupling the first component from the solid support, as shown in step 510 .

5B shows a flow diagram of a method 501 of manufacturing an ultrasonic sensor device 100 including a stabilizing material 101. Method 501 may include step 503 of providing a first component (eg, ultrasonic sensor wafer 102 ) coupled to solid support 108 . Next, one or more features (eg, including one or more cavities 110 ) may be formed on 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 . As shown in step 509, the first component may be released (eg, decoupled) from the solid support 108. As shown in step 511, the method may also include coupling the first component to a second component (eg, an ASIC) after applying the stabilizing material to the first component and decoupling the first component from the solid support.

FIG. 6 shows a flow diagram of a method 600 of manufacturing an ultrasonic sensor device 100 including a stabilizing material 101 . Method 600 may include step 602 of providing a first component (eg, ultrasonic sensor wafer 102 ) coupled to solid support 108 . The first component may be etched or subjected to back grinding to achieve a desired cross-sectional thickness of the first component, as shown in step 604. The stabilizing material 101 may be used to fill one or more cavities of the first component, as shown in step 606. As shown in step 608, the first component may be released (eg, decoupled) from the solid support 108. As shown in step 610, the method may also include coupling the first component to a second component (eg, an ASIC) after applying the stabilizing material to the first component and decoupling the first component from the solid support. Ultrasonic sensor device

The ultrasonic sensor device may include one or more ultrasonic sensors. In many cases, an ultrasound system or device includes one or more ultrasound sensors (e.g., and one or more other internal components, such as a MEMS array, an ultrasound sensor wafer (e.g., a MEMS wafer), an ASIC, and/or The processor) may be located within an internal compartment (eg, interior space) of the ultrasound system or device. In some cases, the internal compartment or space of the ultrasound system may be surrounded (eg, enclosed by the space) by an outer barrier, which may include a housing and acoustic lens 114 . In some cases, an internal compartment or space of an ultrasound system may be defined by an external barrier surrounding (eg, space surrounding) it. In some cases, the systems, devices, or methods described herein may include piezoelectric micromachined ultrasonic sensors (pMUTs). In some cases, the systems, devices, or methods described herein may include one or more capacitive micromachined ultrasonic sensors (cMUTs). Piezoelectric micromachined ultrasonic sensors (pMUTs) may be formed on a substrate such as a semiconductor wafer (eg, a printed circuit board (PCB)). pMUT devices constructed on semiconductor substrates can provide a smaller profile than bulky conventional sensors with bulkier piezoelectric materials. In some cases, pMUTs may also be cheaper to manufacture and/or may allow for less complex and higher performance interconnections between the sensors and additional electronics of the ultrasound device or system.

Micromachined ultrasound sensors (MUTs), which may include pMUTs and/or cMUTs, may include a diaphragm, such as, for example, attached to one or more portions of the interior of an imaging device, such as an ultrasound probe, at the edge of the diaphragm. film). In comparison, traditional bulk piezoelectric (PZT) elements are typically composed of a single piece of solid material. These conventional PZT ultrasound systems and devices can be expensive to manufacture, for example because of the high precision required to cut and install the PZT or ceramic materials that make up the PZT ultrasound systems and devices at appropriate intervals. Additionally, traditional PZT ultrasound systems and devices can have sensor impedances that are significantly higher than the impedance of the transmit/receive electronics of PZT systems and devices, which can negatively impact performance.

In some cases, one or more sensor elements may be configured to transmit and/or receive signals at a specific frequency or bandwidth (eg, where the bandwidth is associated with a center frequency). In some cases, one or more sensor elements may be further configured to transmit and/or receive signals at additional center frequencies and bandwidths. Such multi-frequency sensor 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. Sensor elements or pixels may be configured to emit (e.g., transmit) and/or receive ultrasonic energy (e.g., ultrasonic waveforms, patterns, or pressure waves) at a suitable center frequency (e.g., from 0.1 megahertz (MHz) to 100 MHz) . In some cases, the sensor or pixel may be configured to transmit or receive ultrasonic energy at the following center frequencies: 0.1 MHz to 1 MHz, 0.1 MHz to 1.8 MHz, 0.1 MHz to 3.5 MHz, 0.1 MHz to 5.1 MHz, 0.1 MHz to 10 MHz, 0.1 MHz to 25 MHz, 0.1 MHz to 50 MHz, 0.1 MHz to 100 MHz, 1 MHz to 1.8 MHz, 1 MHz to 3.5 MHz, 1 MHz to 5.1 MHz, 1 MHz to 10 MHz, 1 MHz to 25 MHz, 1 MHz to 50 MHz, 1 MHz to 100 MHz, 1.8 MHz to 3.5 MHz, 1.8 MHz to 5.1 MHz, 1.8 MHz to 10 MHz, 1.8 MHz to 25 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 sensor or pixel may be configured to transmit or receive ultrasonic energy at the following center frequencies: 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 sensor or pixel may be configured to transmit or receive ultrasonic energy at at least the following center frequencies: 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 sensor or pixel may be configured to transmit or receive ultrasonic energy at up to the following center frequencies: 0.1 MHz, 1 MHz, 1.8 MHz, 3.5 MHz, 5.1 MHz, 10 MHz, 25 MHz, 50 MHz, or 100 MHz. junction

A first component of the ultrasonic sensor device, such as a printed circuit board or portion thereof, may be coupled to one or more second components of the ultrasonic sensor device via a joint. In some cases, a junction may provide an electrical connection between a first component and one or more second components. For example, in some cases, a junction may electrically couple a first component and one or more second components. The junction coupling the first component of the ultrasound device and one or more second components of the ultrasound device may be electrically conductive (eg, where the junction includes a conductor). For example, the junction may include conductive material. In some cases, the interface may physically join and/or stabilize the joint between the first component and the second component.

The interface of the ultrasonic sensor device may include one or more conductors (eg, one or more wires). In some cases, a first end of the wire can be coupled to a terminal of the ASIC and a second end of the wire can be coupled to a printed circuit board (PCB). In some cases, the wiring may be coupled to one or more other components of the ultrasonic sensor device (eg, ASIC and/or PCB) via soldering. In some cases, wires may include conductors. For example, the conductive wires may include copper wires, gold wires, silver wires, aluminum wires, or alloys thereof (eg, magnesium aluminum wires or silicon aluminum wires). In some cases, the wires may be coated (eg, palladium-plated wires) and/or doped (eg, where the wires are doped with beryllium).

Ultrasonic sensor devices may include one or more "through silicon through (TSV)" connections. In some cases, TSV connections can electrically couple the ASIC to the PCB. In some cases, the TSV may be coupled to one or more additional components of the ultrasonic sensor device via soldering methods such as flip-chip soldering. The TSV connections may include conductive material from a first (eg, distal) surface of a wafer (eg, a silicon wafer of an integrated circuit, such as an ASIC wafer) to a second (eg, proximal) surface of the wafer. . In some cases, the junction may include solder (eg, at one or more solder points, such as a TSV connection or wire connection).

The interface of the ultrasonic sensor device may include solder. Solder may be used to stabilize or connect one or more other components of the interface (such as wires, TSVs, and/or metal layers of the ASIC or PCB). The solder can have a reflow temperature. In some cases, the solder may melt from the solid phase to the liquid or semi-liquid phase when its temperature reaches the reflow temperature. In some cases, methods for fabricating an ultrasonic sensor device may include bringing all or a portion of the ultrasonic sensor device to a temperature equal to the reflow temperature of the solder (eg, to melt the solder for application to the junction). In some cases, methods for fabricating an ultrasonic sensor device may include maintaining one, plural, or all of the ultrasonic sensor device and/or components thereof at a temperature(s) substantially equal to or lower than the reflow temperature ( For example, a temperature that does not exceed the reflow temperature). In some cases, the reflow temperature of the solder can be as high as 240°C. stable material

As described herein, ongoing damage to ultrasonic device components during manufacturing can be significantly reduced by specifying the materials, methods, and/or sequence of steps used to fabricate the ultrasonic sensor device 100. For example, a material (e.g., stabilizing material 101) is added (e.g., partially or completely coated or filled) to one or more surfaces or cavities of ultrasonic sensor wafer 102 (e.g., after removing ultrasonic sensor wafer 102 from it). prior to removal of the coupled solid support) may substantially reduce the likelihood and/or extent of damage to the ultrasonic sensor wafer 102 during manufacturing. In some cases, all or a portion of the ultrasonic sensor wafer 102 may be brought to (eg, reduced to) a desired cross-sectional thickness (eg, via grinding), etched to include the desired surface architecture (eg, using micron(s)). imaging technique to create the sensor cavity 110) and contact (e.g., partially or completely coated or filled) with a material capable of stabilizing the ultrasonic sensor wafer 102 (e.g., the stabilizing material 101) prior to removing the wafer 102 from the solid support 108 ). For example, the ultrasonic sensor wafer 102 may be etched to include portions that may be filled with a material capable of stabilizing the processed array prior to modifying the thickness of the sensor wafer 102 (e.g., thinning the cavity walls to a desired thickness, such as via lithography) The desired structure (for example, including a plurality of cavities 110).

In some cases, the stabilizing material 101 may be a material that is capable of flowing onto or into surfaces or features of the component. For example, the stabilizing material may be melted and applied to a surface of the component (eg, an interior surface of a cavity 110 of the component, such as an interior surface of the bottom wall 112 of the cavity 110 or the surface of the cavity sidewalls 111 in the ultrasonic sensor wafer 102 ) and allow it to Sets (such as hardening or drying) before the component is subjected to the manipulation steps of the process. In some cases, the stabilizing material may be a flowable material that is applied to a surface of the component (eg, an interior surface of a cavity of the component) and cured (eg, using ultraviolet light) before the component is subjected to the manipulation steps of the process. In some cases, for example, if all or a portion of the ultrasonic sensor wafer 102 (eg, to which the stabilizing material 101 is added) has a reduced cross-sectional thickness (eg, 50 microns or less, 40 microns or less, 30 microns or less or a cross-sectional thickness of 20 microns or less), adding the stabilizing material to all or a portion of the ultrasonic sensor wafer 102 may reduce the risk of damage to the ultrasonic sensor wafer 102 (e.g., due to ultrasonic waves). forces that sensor wafer 102 experiences during fabrication of ultrasonic sensor device 100).

In some cases, the stabilizing material 101 may meet or exceed the acoustic requirements for the acoustic lens 114 used in the ultrasonic sensor device 100. In some cases, stabilizing material 101 may have a speed of sound that is higher than or substantially the same as the speed of sound of the material used to form acoustic lens 114 . In some cases, the stabilizing material 101 may have an acoustic attenuation that is less 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 may have an acoustic impedance that is less than or substantially the same as the acoustic impedance of the acoustic lens 114 . In some cases, the stabilizing material 101 may be used to form the acoustic lens 114 of the ultrasonic sensor device 100 described herein.

Stabilizing material 101 may include monomers. In some cases, stabilizing material 101 may include polysiloxane (eg, polysiloxane-based monomer). In some cases, stabilizing material 101 may include polymers. In some cases, the monomers of stabilizing material 101 may be polymerized into polymers. In some cases, polymeric stabilizing material 101 may include cross-linking all or part of the molecules (eg, monomers) that make up stabilizing material 101 . In some cases, the monomers of stabilizing material 101 can be polymerized by exposing stabilizing material 101 to ultraviolet (UV) light (eg, light having wavelengths from 315 nanometers to 430 nanometers). In some cases, stabilizing material 101 may be polymerized using a polymerizing agent or catalyst (eg, UV-activated platinum catalyst). For example, in some cases, stabilizing material 101 can be polymerized by mixing stabilizing material 101 with a polymerization initiator. In some cases, the polymeric stabilizing material 101 may partially or fully solidify the stabilizing material (eg, where solidification or causes a partial or complete transition of the stabilizing material 101 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 may be performed simultaneously with contacting the ultrasonic sensor wafer 102 (or a portion thereof) with the stabilizing material 101 . In some cases, polymerizing the stabilizing material 101 may be performed after contacting the ultrasonic sensor wafer 102 (or a portion thereof) with the stabilizing material 101 .

In some cases, the stabilizing material 101 may be subjected to a curing or polymerization process (eg, including exposure to UV light) during a curing time. The curing time may depend on the composition and/or amount of cured (or polymerized) stabilizing material 101 . For example, curing conditions that include exposing stabilizing material 101 to UV light may include exposing stabilizing material 101 to UV 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 a favorable curing condition, for example, because in some cases the curing or polymerization process may be performed faster at higher temperatures. In some cases, curing or polymerizing the stabilizing material 101 can be performed at temperatures from 100°C to 18°C, from 80°C to 20°C, from 80°C to 25°C, from 80°C to 35°C, From 80°C to 45°C, from 80°C to 55°C, from 80°C to 65°C, from 60°C to 20°C, from 60°C to 25°C, from 60°C to 35°C or from 60°C to 45°C. In some cases, curing or polymerizing the stabilizing material 101 may include increasing the humidity in the environment of the stabilizing material 101 (eg, exceeding ambient humidity) during the step of polymerizing or curing, for example, to increase the rate of curing or polymerization. In some cases, curing or polymerizing the stabilizing material may include reducing the oxygen content (eg, exceeding ambient oxygenation) of the environment of the stabilizing material 101 during the step of polymerizing or curing, for example, to increase the rate of curing or polymerization.

In some cases, the step of polymerizing the stabilizing material 101 (e.g., wherein the stabilizing material 101 is exposed to UV light) may be performed on one or more interior surfaces of the ultrasonic sensor wafer 102 (e.g., the cavity 110 of the ultrasonic sensor wafer 102 One or more surfaces) are in contact with the stabilizing material 101 (eg, where the stabilizing material 101 includes a monomer, such as a polysiloxy-based monomer). In some cases, the step of polymerizing the stabilizing material 101 (e.g., in which the stabilizing material 101 is exposed to UV light) may be performed before exposing one or more interior surfaces of the ultrasonic wafer 102 (e.g., the cavity 110 of the ultrasonic sensor wafer 102 One or more surfaces) are brought into contact with the stabilizing material 101 (eg, where the stabilizing material 101 includes a monomer, such as a polysiloxy-based monomer).

Stabilizing material 101 may include polysiloxane. In some cases, stabilizing material 101 may include one or more additives (eg, thermal stabilizing additives). In some cases, stabilizing material 101 including one or more additives (eg, one or more thermal stabilizing additives) may have a higher decomposition temperature. In some cases, the decomposition temperature of the stabilizing material 101 can be increased 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 stabilizing material 101 including one or more additives (eg, thermal stabilizing additives) has the following decomposition temperatures: 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 above 280°C. In some cases, the stabilizing material 101 including one or more additives (eg, thermal stabilizing additives) has the following decomposition temperatures: above 180°C, above 200°C, above 210°C, above 220°C, high At 230°C, above 240°C, above 250°C, above 260°C, above 270°C, or above 280°C. Some thermal stabilizing additives that can be used in stabilizing material 101 include iron, cerium and titanium oxide. In some cases, the thermal stabilizing additive may have a particle size of 10 microns or less.

In many cases, the materials used to form the acoustic lenses in existing ultrasonic sensor devices have decomposition temperatures below the solder reflow temperature. In many cases, stable materials 101 that have a decomposition temperature above the solder reflow temperature (eg, of the solder used to fabricate ultrasonic sensor device 100) may be used in the methods and systems described herein. In some cases, using a stabilizing material 101 that has a decomposition temperature higher than the solder reflow temperature may reduce the negative impact of the stabilizing material by the ultrasonic sensor device fabrication steps after the stabilizing material is added to the ultrasonic sensor wafer (e.g., relative to sound intelligibility and/or melting). For example, using a stabilizing material 101 with a decomposition temperature higher than the reflow temperature of the solder used to couple the ASIC to the PCB after adding the stabilizing material 101 to the ultrasonic sensor wafer 102 may prevent the stabilizing material 101 from adding heat during manufacturing. to melt or degrade when coupling the ASIC to the PCB.

The stabilizing material 101 may exhibit acoustic attenuation (eg, after addition to a silicon-based wafer or portion thereof and curing). For example, the stabilizing material 101 may have a sound attenuation of about 0.10 decibels per millimeter (dB/mm) to about 50.0 dB/mm. In some cases, the stabilizing material 101 may have a sound attenuation 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 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 0.10 dB/mm to about 30.0 dB/mm, about 0.10 dB/mm to about 50.0 dB/mm, about 0.25 dB/ mm to about 0.50 dB/mm, about 0.25 dB/mm to about 0.75 dB/mm, about 0.25 dB/mm to about 1.00 dB/mm, about 0.25 dB/mm to about 5.00 dB/mm, about 0.25 dB/mm to About 10.0 dB/mm, about 0.25 dB/mm to about 15.0 dB/mm, about 0.25 dB/mm to about 20.0 dB/mm, about 0.25 dB/mm to about 25.0 dB/mm, about 0.25 dB/mm to about 30.0 dB/mm, about 0.25 dB/mm to about 50.0 dB/mm, about 0.50 dB/mm to about 0.75 dB/mm, about 0.50 dB/mm to about 1.00 dB/mm, about 0.50 dB/mm to about 5.00 dB/ mm, about 0.50 dB/mm to about 10.0 dB/mm, about 0.50 dB/mm to about 15 dB/mm, about 0.50 dB/mm to about 20.0 dB/mm, about 0.50 dB/mm to about 25.0 dB/mm, About 0.50 dB/mm to about 30.0 dB/mm, about 0.50 dB/mm to about 50.0 dB/mm, about 0.75 dB/mm to about 1.00 dB/mm, about 0.75 dB/mm to about 5.00 dB/mm, about 0.75 dB/mm to about 10.0 dB/mm, about 0.75 dB/mm to about 15.0 dB/mm, about 0.75 dB/mm to about 20.0 dB/mm, about 0.75 dB/mm to about 25.0 dB/mm, about 0.75 dB/ mm to about 30.0 dB/mm, about 0.75 dB/mm to about 50.0 dB/mm, about 1.00 dB/mm to about 5.00 dB/mm, about 1.00 dB/mm to about 10.0 dB/mm, about 1.00 dB/mm to About 15.0 dB/mm, about 1.00 dB/mm to about 20.0 dB/mm, about 1.00 dB/mm to about 25.0 dB/mm, about 1.00 dB/mm to about 30.0 dB/mm, about 1.00 dB/mm to about 50.0 dB/mm, about 5.00 dB/mm to about 10.0 dB/mm, about 5.00 dB/mm to about 15.0 dB/mm, about 5.00 dB/mm to about 20.0 dB/mm, about 5.00 dB/mm to about 25.0 dB/ mm, about 5.00 dB/mm to about 30.0 dB/mm, about 5.00 dB/mm to about 50.0 dB/mm, about 10.0 dB/mm to about 15.0 dB/mm, about 10.0 dB/mm to about 20.0 dB/mm, About 10.0 dB/mm to about 25.0 dB/mm, about 10.0 dB/mm to about 30.0 dB/mm, about 10.0 dB/mm to about 50.0 dB/mm, about 15.0 dB/mm to about 20.0 dB/mm, about 15.0 dB/mm to about 25.0 dB/mm, about 15.0 dB/mm to about 30.0 dB/mm, about 15.0 dB/mm to about 50.0 dB/mm, about 20.0 dB/mm to about 25.0 dB/mm, about 20.0 dB/ mm to approximately 30.0 dB/mm, approximately 20.0 dB/mm to approximately 50.0 dB/mm, approximately 25.0 dB/mm to approximately 30.0 dB/mm, approximately 25.0 dB/mm to approximately 50.0 dB/mm, or approximately 30.0 dB/mm to approximately About 50.0 dB/mm. In some cases, the stabilizing material 101 may have the following sound attenuation: 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 stabilizing material 101 can have a sound attenuation 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 the following sound attenuation: up to about 0.10 dB/mm, up to 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. mm, approximately 10.0 dB/mm, approximately 15.0 dB/mm, approximately 20.0 dB/mm, approximately 25.0 dB/mm, approximately 30.0 dB/mm, or approximately 50.0 dB/mm. Stable material 101 with acoustic attenuation (e.g., after addition to at least a portion of a silicon-based wafer or portion thereof) may improve the transmission of acoustic (e.g., ultrasonic) energy waves, e.g., during operation of ultrasonic sensor device 100 . Overstabilized Materials 101. Application

In some cases, the imaging system or device 100 described herein may be used for (eg, non-invasive) medical imaging, lithotripsy, localized tissue heating for therapeutic intervention, high-intensity focused ultrasound (HIFU) surgery, and/or or flow measurement in pipes (or loudspeaker and microphone arrays) for non-medical purposes. In some cases, the imaging systems or devices described herein may be used, for example, to determine the direction and/or velocity of fluid flow (eg, blood flow) in arteries and/or veins using Doppler mode imaging. . In some cases, the imaging systems or devices described herein can be used to measure tissue stiffness.

In some cases, the imaging system or device 100 described herein may be configured to perform one-dimensional imaging (eg, A-scan imaging). In some cases, the imaging system or device 100 described herein may be configured to perform two-dimensional imaging (eg, B-scan imaging). In some cases, the imaging system or device 100 described herein may be configured to perform three-dimensional imaging (eg, 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 switch to different modes (eg, between modes), including linear mode or sector mode. In some cases, imaging system or device 100 may be configured electronically under program control (eg, by a user).

In many cases, the imaging system or device 100 (eg, the probe of the imaging system or device 100) may be portable. For example, imaging system or device 100 may include (eg, housed within a housing) a handheld housing that may house one or more sensor elements, pixels or arrays, ASICs, control circuitry, and/or computing devices. In some cases, imaging system or device 100 may include a battery. some definitions

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 invention belongs.

As used in this specification and appended claims, the singular forms "a", "a" and "the" include plural referents unless the context clearly dictates otherwise. Unless otherwise stated, any reference to "or" herein is intended to include "and/or".

Reference in this specification to "some embodiments," "further embodiments," or "particular embodiments" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases "in some embodiments" or "in further embodiments" or "in particular embodiments" appearing variously throughout this specification are not necessarily all referring to the same embodiment. Additionally, particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

Although preferred embodiments of the present invention have been shown and described herein, those skilled in the art will understand that these embodiments are illustrative only. Many modifications, changes and substitutions will now occur to those skilled in the art without departing from the present invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention.

100: Ultrasonic sensor device 101: Stable materials 102: Ultrasonic sensor wafer 104:Metal back layer 106:Adhesive 108: Solid support/carrier substrate 110: cavity 111: Cavity side wall 112: Bottom wall 114:Acoustic lens 116:Application Specific Integrated Circuit (ASIC) 117:Metal layer 118: Non-conductive crystal bonding material 119: Non-conductive primer layer 120: Printed circuit board (PCB) 121:Metal layer 122: Through silicon (TSV) connection 124: Flip chip solder 126:Wiring 130: Initial cross-section thickness 131: Reduced cross-sectional thickness 500:Method 501:Method 502: Step 503: Step 504: Step 505: Step 506: Step 507:Step 508:Step 509: Step 510: Steps 511: Steps 600:Method 602: Step 604: Step 606: Step 608: Step 610: Steps 652:Step 654:Step 702: Step 704: Step 902: Step 904: Step 906:Step 908:Step 910: Steps 912: Steps 914: Steps

A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description and the accompanying drawings which illustrate illustrative embodiments, in which:

Figures 1A and 1B each show a schematic diagram showing a portion of an ultrasonic sensor device, according to an embodiment.

Figure 2A shows a schematic flow diagram of exemplary steps for fabricating an ultrasonic sensor device according to an embodiment.

Figure 2B shows a schematic flow diagram of exemplary steps for fabricating an ultrasonic sensor device according to an embodiment.

Figure 3 shows a schematic flow diagram of exemplary steps for fabricating an ultrasonic sensor device according to an embodiment.

Figure 4 shows a schematic flow diagram of exemplary steps for fabricating an ultrasonic sensor device according to an embodiment.

Figure 5A shows a flow diagram of an exemplary method for manufacturing an ultrasonic sensor device, according to an embodiment.

Figure 5B shows a flow diagram of an exemplary method for fabricating an ultrasonic sensor device, according to an embodiment.

Figure 6 shows a flow diagram of an exemplary method for fabricating an ultrasonic sensor device, according to an embodiment.

100: Ultrasonic sensor device

101: Stable materials

102: Ultrasonic sensor wafer

104:Metal back layer

106:Adhesive

108: Solid support/carrier substrate

110: cavity

111: Cavity side wall

112: Bottom wall

114:Acoustic lens

116:Application Specific Integrated Circuit (ASIC)

117:Metal layer

118: Non-conductive crystal bonding material

120: Printed circuit board (PCB)

121:Metal layer

126:Wiring

130: Initial cross-section thickness

131: Reduced cross-sectional thickness

902: Step

904: Step

906:Step

908:Step

910: Steps

912: Steps

Claims (53)

A method of manufacturing an ultrasonic sensor device, the method comprising: causing a plurality of cavities to be formed in the sensor wafer coupled to the carrier substrate; bringing one or more interior surfaces of one or more of the plurality of cavities into contact with a stabilizing material; and The sensor wafer is decoupled from the carrier substrate after contacting the one or more inner surfaces with the stabilizing material. The method of claim 1, further comprising reducing a cross-sectional thickness of at least a portion of the sensor wafer. The method of claim 2, wherein the cross-sectional thickness of the sensor wafer is reduced to no more than 75 microns. The method of claim 2, wherein the cross-sectional thickness of the sensor wafer is reduced to no more than 50 microns. The method of claim 2, wherein reducing the cross-sectional thickness of at least a portion of the sensor wafer is performed before causing the plurality of cavities to be formed in the sensor wafer. The method of claim 2, wherein reducing the cross-sectional thickness of at least a portion of the sensor wafer is performed after causing the plurality of cavities to be formed in the sensor wafer. The method of claim 2, wherein reducing the cross-sectional thickness of at least a portion of the sensor wafer is performed after contacting the one or more inner surfaces with the stabilizing material. The method of claim 2, wherein reducing the cross-sectional thickness of at least a portion of the sensor wafer is performed prior to contacting the one or more inner surfaces with the stabilizing material. The method of claim 1, wherein the plurality of cavities are formed in the sensor wafer using photolithography. The method of claim 1, wherein forming the plurality of cavities in the sensor wafer includes etching the plurality of cavities in the sensor wafer. The method of claim 2, wherein reducing the cross-sectional thickness of at least a portion of the sensor wafer includes back grinding a surface of the sensor wafer. The method of claim 2, wherein reducing the cross-sectional thickness of at least a portion of the sensor wafer includes etching a cavity sidewall of the sensor wafer. The method of claim 8 or claim 12, wherein the etching includes wet etching or plasma etching. The method of claim 1, wherein the sensor wafer coupled to the carrier includes a cross-sectional thickness of 100 microns. The method of claim 1, wherein the sensor wafer coupled to the carrier includes a cross-sectional thickness of 75 microns. The method of claim 15, wherein the sensor wafer coupled to the carrier includes a cross-sectional thickness of 50 microns. The method of claim 1, wherein contacting the one or more inner 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). By. The method of claim 1, further comprising polymerizing the stabilizing material. The method of claim 18, wherein polymerizing the stabilizing material is performed after contacting the one or more inner surfaces with the stabilizing material. The method of claim 18, wherein polymerizing the stabilizing material is performed simultaneously with contacting the one or more inner surfaces with the stabilizing material. The method of claim 18, wherein polymerizing the stabilizing material includes exposing the stabilizing material to ultraviolet (UV) light. The method of claim 1, wherein contacting the one or more interior surfaces with the stabilizing material includes filling the one or more cavities with the stabilizing material up to a level between the stabilizing material and one or more cavity sidewalls of the one or more cavities. Flush. The method of claim 1, wherein contacting the one or more interior surfaces with the stabilizing material includes filling the one or more cavities with the stabilizing material until the stabilizing material exceeds the one or more cavity sidewalls of the one or more cavities. high. The method of claim 1, wherein contacting the one or more interior surfaces with the stabilizing material includes filling the one or more cavities with the stabilizing material until the stabilizing material is below one or more cavity sidewalls of the one or more cavities. the height. The method of claim 1, further comprising: singulating the sensor wafer into one or more ultrasonic sensor wafers including the plurality of cavities and the stabilizing material; and coupling an acoustic lens to the stabilizing material. material or one or more of the sensor chips of the one or more ultrasonic sensor chips. The method of claim 25, wherein the acoustic lens extends over and across each of the one or more cavities. The method of claim 25, wherein the acoustic lens is formed of the same material as the stabilizing material. The method of claim 25, wherein the acoustic lens is formed of a material different from the stabilizing material. The method of claim 25, wherein the acoustic lens is formed from a lens material, and wherein the lens material and the stabilizing material have substantially the same one or more of acoustic velocity, acoustic attenuation, or acoustic impedance. The method of claim 1, further comprising coupling one or more ultrasonic sensor wafers singulated from the sensor wafer including the plurality of cavities and the stabilizing material to an application specific integrated circuit (ASIC). The method of claim 30, wherein the one or more ultrasonic sensor chips are coupled to the ASIC by flip chip soldering. The method of claim 31, wherein the stabilizing material has a decomposition temperature higher than a reflow temperature of solder used to couple the one or more ultrasonic sensor chips to the ASIC. The method of claim 30, further comprising coupling the ASIC to a printed circuit board (PCB). The method of claim 33, wherein the ASIC is coupled to the PCB by wire bonding or by flip chip soldering. The method of claim 33, wherein the stabilizing material has a decomposition temperature higher than a reflow temperature of solder used to couple the ASIC to the PCB. The method of claim 1, wherein the stabilizing material includes polysiloxane. The method of claim 36, wherein the stabilizing material includes one or more heat stabilizer additives selected from the group consisting of iron, cerium and titanium oxide. The method of claim 1, wherein the stable material has a decomposition temperature higher than 240°C. The method of claim 1, wherein the ultrasonic sensor device includes a pMUT sensor. The method of claim 1, wherein the ultrasonic sensor device includes a cMUT sensor. An ultrasonic sensor device including: a sensor chip including a plurality of cavities; a stabilizing material in contact with at least a portion of the interior surface of one or more of the plurality of cavities; an acoustic lens extending over and across the plurality of cavities and formed from a lens material, The lens material and the stabilizing material have substantially the same one or more of sound velocity, sound attenuation or sound impedance. The device of claim 41, wherein at least a portion of the sensor wafer has a cross-sectional thickness of at most 50 microns. The device of claim 41, further comprising an application specific integrated circuit (ASIC) and a printed circuit board (PCB), wherein the ASIC is coupled to the PCB by a junction including solder. The device of claim 43, wherein the decomposition temperature of the stabilizing material is greater than the reflow temperature of the solder. The device of claim 43, wherein the reflow temperature of the solder is 240°C. The device of claim 41, wherein the stabilizing material includes one or more thermal stabilizer additives selected from the group consisting of iron, cerium and titanium oxide. The device of claim 41, wherein the stabilizing material has acoustic attenuation. The device of claim 41, wherein the acoustic lens is formed of a material different from the stabilizing material. The device of claim 41, wherein the lens material has a decomposition temperature equal to or greater than the decomposition temperature of the stabilizing material. The device of claim 41, wherein the lens material has a decomposition temperature lower than the decomposition temperature of the stabilizing material. The device of claim 41, wherein the sensor wafer has a cross-sectional thickness of at most 50 microns across the entire length and width of the sensor wafer. The device of claim 41, wherein the ultrasonic sensor device includes a pMUT sensor. The device of claim 41, wherein the ultrasonic sensor device includes a cMUT sensor.