Acoustic resonator device

Abstract

A method for manufacturing a bulk acoustic wave resonator structure for a fluid device may include a first step of disposing a first conductive material on a portion of a first surface of a substrate to form at least a portion of a first electrode; then, disposing a piezoelectric material on the first electrode; next, disposing a second conductive material on the piezoelectric material to form at least a portion of a second electrode; then, disposing an acoustic energy management structure on a first side of the bulk acoustic wave resonator; next, disposing a third conductive material on a portion of the second conductive material extending beyond the bulk acoustic wave resonator; and finally, removing a portion of a second surface of the substrate to expose a chemical mechanical connection at the first electrode on a second side of the bulk acoustic wave resonator.

Description

[0001] Cross-reference to related applications

[0002] This application is a non-provisional application of U.S. Provisional Patent Application Serial No. 62 / 844,000, filed on May 6, 2019, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure generally relates to acoustic resonator devices, including acoustic sensors and fluid devices incorporating acoustic resonators, as well as related systems suitable for biosensing or biochemical sensing applications. Background Technology

[0004] A biosensor (or biological sensor) is an analytical device comprising a biological element and a transducer that converts the biological response into an electrical signal. Some biosensors involve selective biochemical reactions between specifically binding materials (e.g., antibodies, receptors, ligands, etc.) and target substances (e.g., molecules, proteins, DNA, viruses, bacteria, etc.), and the products of this highly specific reaction are converted by the transducer into measurable quantities. Other sensors may utilize non-specific binding materials capable of binding multiple types or classes of molecules or other parts that may be present in the sample. The term "functionalized material" is used herein to generally refer to both specific and non-specific binding materials. The conduction methods used with biosensors may be based on a variety of principles, such as electrochemical, optical, electrical, acoustic, etc. Among these, acoustic conduction offers many potential advantages, such as real-time, label-free, and low-cost operation, as well as exhibiting high sensitivity.

[0005] Acoustic wave devices employ sound waves propagating through specially bonded materials or on their surfaces, where any change in the characteristics of the propagation path affects the wave velocity and / or amplitude. Due to the need to provide microscale features suitable for facilitating high-frequency operation, acoustic wave devices are typically fabricated using microelectromechanical systems (MEMS) manufacturing techniques. The presence of functionalized materials on or above the active region of the acoustic wave device allows the analyte to be bonded to the functionalized material, thereby altering the mass vibrating by the sound waves and changing the wave propagation characteristics (e.g., velocity, thus changing the resonant frequency). Changes in velocity can be monitored by measuring the frequency, amplitude-amplitude, and / or phase characteristics of the acoustic wave device and can be correlated with the measured physical quantity.

[0006] Typically, BAW devices are fabricated using microelectromechanical systems (MEMS) fabrication techniques to provide microscale features suitable for facilitating high-frequency operation. In the context of biosensors, functionalized materials (e.g., specifically binding materials; also known as bioactive probes or reagents) can be deposited on the sensor surface using various techniques, such as microarray spotting (also known as microarray printing). Functionalized materials that provide non-specific binding utility (e.g., allowing the binding of multiple types or kinds of molecules) can also be used in certain applications, such as chemical sensing.

[0007] Existing processes for manufacturing resonator arrays present numerous challenges. For instance, the length of electrical leads increases as multiple rows of resonators are placed within the fluid path. For example, if there are four resonators across the width of the fluid path, the lead length to the resonator at the center of the fluid path will be very long. This, in turn, makes it difficult to solve high-density resonator sensor arrays. For example, sensor arrays can range from 2×2 (4 in total) to 50×50 (2500 in total). Furthermore, the fluid height of the sensor channel is directly related to the height of the laminate.

[0008] A high-density BAW sensor array may be required, which provides the advantages of short electrical leads, low fluid channel height, and high reliability by isolating electrical connections and fluid interfaces on opposite sides of the BAW die. Those skilled in the art will understand the scope of this disclosure and implement its additional aspects after reading the following detailed description in conjunction with the accompanying drawings. Summary of the Invention

[0009] The present disclosure generally relates to a method of manufacturing an apparatus including a bulk acoustic wave (BAW) resonator sensor, which can be electrically connected to a printed circuit board more efficiently and easily. The method may include forming a BAW resonator on a first surface of a substrate and removing a portion of the substrate from an opposite surface. The method may also optionally include flip-chip mounting.

[0010] According to the principles of this disclosure, some aspects relate to a method of manufacturing a bulk acoustic wave resonator structure for a fluid device. The method may include a first step of disposing a first conductive material over a portion of a first surface of a substrate to form at least a portion of a first electrode, the substrate having a second surface opposite to the first surface. A piezoelectric material may then be disposed over the first electrode. Next, a second conductive material may be disposed over the piezoelectric material to form at least a portion of a second electrode. The second conductive material extends substantially parallel to the first surface of the substrate and extends at least partially over the first conductive material. The overlapping region of the first conductive material, the piezoelectric material, and the second conductive material forms a bulk acoustic wave resonator having a first side and an opposing second side. An acoustic energy management structure is then disposed over the first side of the bulk acoustic wave resonator. Next, a third conductive material is disposed over the portion of the second conductive material extending beyond the bulk acoustic wave resonator, wherein the third conductive material forms an interconnect extending over the acoustic energy management structure in a direction substantially perpendicular to the first surface of the substrate. Finally, a portion of the second surface of the substrate is removed to expose a chemical mechanical connection at the first electrode on the second side of the bulk acoustic wave resonator.

[0011] According to the principles of this disclosure, other aspects relate to a method of manufacturing a bulk acoustic wave resonator structure for a fluid device. The method may include a first step of disposing a first conductive material over a portion of a first surface of a substrate to form at least a portion of a first electrode, the substrate having a second surface opposite to the first surface. A piezoelectric material may then be disposed over the first electrode. Next, a second conductive material may be disposed over the piezoelectric material to form at least a portion of a second electrode. The second conductive material extends substantially parallel to the first surface of the substrate and extends at least partially over the first conductive material. The overlapping region of the first conductive material, the piezoelectric material, and the second conductive material forms a bulk acoustic wave resonator having a first side and an opposing second side. A reflector structure, serving as an acoustic energy management structure, is then disposed over the first side of the bulk acoustic wave resonator. Next, a third conductive material is disposed over the portion of the second conductive material extending beyond the bulk acoustic wave resonator, wherein the third conductive material forms an interconnect extending over the reflector structure in a direction substantially perpendicular to the first surface of the substrate. Finally, a portion of the second surface of the substrate is removed to expose a chemical mechanical connection at the first electrode on the second side of the bulk acoustic wave resonator.

[0012] According to the principles of this disclosure, other aspects relate to a method of manufacturing a bulk acoustic wave resonator structure for a fluid device. The method may include a first step of disposing a first conductive material over a portion of a first surface of a substrate to form at least a portion of a first electrode, the substrate having a second surface opposite to the first surface. A piezoelectric material may then be disposed over the first electrode. Next, a second conductive material may be disposed over the piezoelectric material to form at least a portion of a second electrode. The second conductive material extends substantially parallel to the first surface of the substrate and extends at least partially over the first conductive material. The overlapping region of the first conductive material, the piezoelectric material, and the second conductive material forms a bulk acoustic wave resonator having a first side and an opposing second side. A gas cavity, serving as an acoustic energy management structure, is then disposed over the first side of the bulk acoustic wave resonator. Next, a third conductive material is disposed over the portion of the second conductive material extending beyond the bulk acoustic wave resonator, wherein the third conductive material forms an interconnect extending over the gas cavity in a direction substantially perpendicular to the first surface of the substrate. Finally, a portion of the second surface of the substrate is removed to expose a chemical mechanical connection at the first electrode on the second side of the bulk acoustic wave resonator.

[0013] Details of one or more aspects of this disclosure are set forth in the accompanying drawings and the following description. Other features, objects, and advantages of the technology described in this disclosure will be apparent from the specification, the drawings, and the claims. Attached Figure Description

[0014] The accompanying drawings, which are included in and form part of this specification, illustrate some aspects of this disclosure and, together with the specification, serve to explain the various principles of this disclosure.

[0015] Figures 1A to 1J This is a schematic diagram of the apparatus at various stages in an illustrative method for manufacturing a structure containing a volumetric acoustic wave according to aspects of this disclosure.

[0016] Figure 2 This is a schematic cross-sectional view illustrating the sacrificial layer and silicon substrate during the method of forming an exemplary bulk acoustic structure according to aspects of this disclosure.

[0017] Figure 3 This describes the method for forming an example volumetric acoustic structure according to aspects of this disclosure. Figure 2 A schematic cross-sectional view of the silicon oxide layer on the layer.

[0018] Figure 4 This describes the method for forming an example volumetric acoustic structure according to aspects of this disclosure. Figure 3 A schematic cross-sectional view of the silicon nitride layer on the layer.

[0019] Figure 5This illustrates the optional removal during the method of forming an example bulk acoustic structure according to aspects of this disclosure. Figure 4 A schematic cross-sectional view of the sacrificial layer on the layer.

[0020] Figure 6 This describes the method for forming an example volumetric acoustic structure according to aspects of this disclosure. Figure 5 A schematic cross-sectional view of the electrodes and silicon oxide on the layer.

[0021] Figure 7 This describes the method for forming an example volumetric acoustic structure according to aspects of this disclosure. Figure 6 A schematic cross-sectional view of an inclined shear axis piezoelectric film on a layer.

[0022] Figure 8 This describes the method for forming an example volumetric acoustic structure according to aspects of this disclosure. Figure 7 A schematic cross-sectional view of the second electrode layer on the piezoelectric layer.

[0023] Figure 9 This describes the method for forming an example volumetric acoustic structure according to aspects of this disclosure. Figure 8 A schematic cross-sectional view of the stacked layers on the layer.

[0024] Figure 10 This describes the method for forming an example volumetric acoustic structure according to aspects of this disclosure. Figure 9 A schematic cross-sectional view of the protective layer on the layer.

[0025] Figure 11 This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure. Figure 10 A schematic cross-sectional view of an acoustic energy management structure extending from a portion of the layer.

[0026] Figure 12 This illustrates the method of forming an exemplary bulk acoustic structure according to aspects of this disclosure, for electrical connection relative to... Figure 10 A schematic cross-sectional view of the interconnected layers of plates.

[0027] Figure 13 This illustrates the method of removing a portion of a substrate relative to an exemplary bulk acoustic structure during the formation of an exemplary bulk acoustic structure according to aspects of this disclosure. Figure 12 A schematic cross-sectional view showing how the layer reduces the substrate thickness.

[0028] Figure 14A , 14B 14C illustrates an additional portion of the substrate being dry-etched during the method of forming an example bulk acoustic structure according to aspects of this disclosure to form a structure relative to... Figure 13Schematic cross-sectional and perspective views of the fluid path in the layer.

[0029] Figure 15A , 15B Figures 15C, 15D, and 15E are schematic cross-sectional views, cross-sectional views, and perspective views illustrating a BAW die flip chip mounted on a board relative to the bulk acoustic wave structure of FIG14 during a method of forming an example bulk acoustic wave structure according to aspects of this disclosure.

[0030] Figure 16 This is a schematic cross-sectional view illustrating the attachment of a fluid wall structure relative to the bulk acoustic structure of FIG14 during a method of forming an example fluid device according to aspects of this disclosure.

[0031] Figure 17A , 17B 17C illustrates the method of forming an example bulk acoustic structure according to aspects of this disclosure, relative to... Figure 16 A schematic cross-sectional view of the bottom filler of the wicking device under the flip-chip mounted die.

[0032] Figure 18 This is a schematic cross-sectional view illustrating the silanization, functionalization printing, and dotting of the apparatus of FIG17 during the method of forming an example bulk acoustic structure according to aspects of this disclosure.

[0033] Figure 19A , 19B 19C illustrates the method of forming an exemplary bulk acoustic structure according to aspects of this disclosure, relative to... Figure 18 A schematic cross-sectional view of the device attached to the fluid cavity cover of the fluid wall structure.

[0034] Figure 20 This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure, relative to... Figure 18 A schematic diagram of an additional method by which the device attaches the fluid chamber cover to the fluid wall structure.

[0035] Figure 21 This is a schematic cross-sectional view illustrating a silicon substrate on which silicon oxide and silicon nitride films are deposited during a method for forming an exemplary bulk acoustic structure according to aspects of this disclosure.

[0036] Figure 22 This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure, relative to... Figure 21 A schematic cross-sectional view of electrode formation, silicon oxide deposition, and surface planarization using a chemical mechanical polishing (CMP) process.

[0037] Figure 23 This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure, relative to... Figure 22 A schematic cross-sectional view of the deposited tilted shear axis piezoelectric film.

[0038] Figure 24 This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure, relative to... Figure 23 A schematic cross-sectional view of the deposition and patterning of the second electrode above the piezoelectric layer.

[0039] Figure 25 This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure, relative to... Figure 24 Schematic cross-sectional view of deposited and patterned accumulation layers.

[0040] Figure 26 This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure, relative to... Figure 25 A schematic cross-sectional view of the deposited and patterned protective layer.

[0041] Figure 27 This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure, relative to... Figure 26 A schematic cross-sectional view of a acoustic reflector fabricated above a resonator.

[0042] Figure 28 This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure, relative to... Figure 27 A schematic cross-sectional view of the bumps used for electrical connection to the board.

[0043] Figure 29 This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure, relative to... Figure 28 A schematic cross-sectional view of a portion of a back-side-grinding substrate to reduce substrate thickness.

[0044] Figure 30 This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure, relative to... Figure 29 A schematic cross-sectional view of a portion of a substrate etched by dry etching to form fluid paths in the region of the resonator.

[0045] Figure 31 This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure, relative to... Figure 30 A schematic cross-sectional view of a BAW biosensor die flip chip mounted on a printed circuit board.

[0046] Figure 32A and 32B This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure, relative to... Figure 31 Attached are schematic cross-sectional and perspective views of the independent fluid wall structure.

[0047] Figure 33 This illustrates the method of forming an example bulk acoustic structure according to aspects of this disclosure, showing relative to... Figure 32A and 32B A schematic cross-sectional view of the device after the bottom filler is sucked up under the die in a flip-chip mounted die.

[0048] Figure 34 This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure, relative to... Figure 33 A schematic cross-sectional view of the completed silanization, functionalization printing, and dotting.

[0049] Figure 35 This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure, relative to... Figure 34 A schematic cross-sectional view of the fluid cavity cover attached to the fluid wall structure.

[0050] Figure 36 This is a schematic plan view of the exposed resonator side and independent wall of a BAW sensor die during the method of forming an exemplary bulk acoustic structure according to aspects of this disclosure.

[0051] Figure 37 This illustrates the method of attaching a cover to an exemplary bulk acoustic structure during the formation of the structure according to aspects of this disclosure. Figure 31 A schematic cross-sectional view of an alternative method on a BAW die.

[0052] Figure 38 This is a schematic cross-sectional view illustrating a silicon-on-insulator (SOI) wafer that can be used in a method of forming an exemplary bulk acoustic structure according to aspects of this disclosure.

[0053] Figure 39 This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure, relative to... Figure 38 A schematic cross-sectional view of the patterned hard mask and wet etching of the top silicon.

[0054] Figure 40 This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure, relative to... Figure 39 A schematic cross-sectional view of the deposited silicon nitride film.

[0055] Figure 41 This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure, relative to... Figure 40 A schematic cross-sectional view of electrode formation, silicon oxide deposition, and surface planarization using a CMP process.

[0056] Figure 42This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure, relative to... Figure 41 A schematic cross-sectional view of the deposited tilted shear axis piezoelectric film.

[0057] Figure 43 This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure, relative to... Figure 42 A schematic cross-sectional view of electrodes deposited and patterned above a piezoelectric layer.

[0058] Figure 44 This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure, relative to... Figure 43 Schematic cross-sectional view of deposited and patterned accumulation layers.

[0059] Figure 45 This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure, relative to... Figure 44 A schematic cross-sectional view of an example of a gas cavity and acoustic energy management structure fabricated on a resonator.

[0060] Figure 46 This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure, relative to... Figure 45 A schematic cross-sectional view of the bumps used for electrical connection to the board.

[0061] Figure 47 This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure, relative to... Figure 46 A schematic cross-sectional view of a substrate with back-side grinding to reduce substrate thickness.

[0062] Figure 48 This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure, relative to... Figure 47 A schematic cross-sectional view of the BAW biosensor die flip chip mounted on the board.

[0063] Figure 49A and 49B This explains the relative to Figure 48 Attached are schematic cross-sectional and plan views of the independent fluid wall structure.

[0064] Figure 50 This is a schematic cross-sectional view illustrating the bottom filler of the die under the flip-chip mount of FIG49 during the method of forming an exemplary bulk acoustic structure according to aspects of this disclosure.

[0065] Figure 51 This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure, relative to... Figure 50 A schematic cross-sectional view of the silanization, functionalization printing, and dotting process.

[0066] Figure 52A and 52B This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure, relative to... Figure 51 Schematic and planar cross-sectional view of the fluid cavity cover attached to the fluid wall structure.

[0067] Figure 53 This illustrates the method for forming an exemplary bulk acoustic structure according to aspects of this disclosure, during the process relative to... Figure 44 A schematic cross-sectional view of an example of fabricating an acoustic reflector and acoustic energy management structure on a resonator.

[0068] Figure 54 This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure, relative to... Figure 53 A schematic cross-sectional view of the bumps used for electrical connection to the board.

[0069] Figure 55 This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure, relative to... Figure 54 A schematic cross-sectional view of a substrate back-grinding process to reduce substrate thickness.

[0070] Figure 56 This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure, relative to... Figure 55 A schematic cross-sectional view of the BAW biosensor die flip chip mounted on the board.

[0071] Figure 57 This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure, relative to... Figure 56 A schematic cross-sectional view of the attached independent fluid wall structure.

[0072] Figure 58 This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure, relative to... Figure 57 A schematic cross-sectional view of the bottom filler of the die under the flip-chip mount.

[0073] Figure 59 This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure, relative to... Figure 58 A schematic cross-sectional view of the silanization, functionalization printing, and dotting process.

[0074] Figure 60 This illustrates the method for forming an example volumetric acoustic structure according to aspects of this disclosure, relative to... Figure 59 A schematic cross-sectional view of the fluid cavity cover attached to the fluid wall structure.

[0075] Figure 61 This is a schematic plan view of the interconnect side and the separate walls of the BAW sensor die after the method for forming an exemplary bulk acoustic structure according to aspects of this disclosure has been completed.

[0076] Figure 62 This is a schematic plan view of the exposed resonator side and independent walls of the BAW sensor die after the method of forming an exemplary bulk acoustic structure according to aspects of this disclosure has been completed.

[0077] The accompanying drawings are not necessarily drawn to scale. The same reference numerals used in the drawings refer to the same parts. However, it will be understood that the use of reference numerals to refer to parts in the drawings is not intended to limit the parts labeled with the same reference numerals in another drawing. Detailed Implementation

[0078] In the following detailed description, several specific embodiments of compounds, compositions, devices, systems, and methods are disclosed. It should be understood that other embodiments are conceivable and can be made without departing from the scope or spirit of this disclosure. Therefore, the following detailed description should not be considered limiting.

[0079] It will be understood that while the terms first, second, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, without departing from the scope of this disclosure, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0080] In this document, relative terms such as “below” or “above” or “upper” or “lower” or “top” or “bottom” or “horizontal” or “vertical” may be used to describe the relationship between one element, layer, or region and another element, layer, or region as shown in the figures. It should be understood that these terms, and those discussed above, are intended to include different orientations of the device other than those shown in the figures.

[0081] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. As used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It will be further understood that the terms “comprising” and “including” as used herein specify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. As used herein, the terms “proximate” and “adjacent” applied to a particular layer or element mean a state of being close to or near another layer or element, and include the possibility that one or more intermediate layers or elements may be in direct contact with or on another layer or element, unless otherwise specified herein.

[0082] In the case of piezoelectric crystal resonators, sound waves can manifest as bulk acoustic waves (BAW) propagating through the interior of the substrate, or surface acoustic waves (SAW) propagating on the surface of the substrate. SAW devices involve the propagation of sound waves (typically two-dimensional Rayleigh waves) along the surface of the piezoelectric material using interdigital transducers, with the waves confined to a penetration depth of approximately one wavelength. In BAW devices, three wave modes can propagate: one longitudinal mode (representing a shear wave, also known as a compression / stretching wave) and two shear modes (representing a shear wave, also known as a transverse wave), where the longitudinal and shear modes respectively identify vibrations of particle motion parallel or perpendicular to the wave propagation direction. The longitudinal mode is characterized by compression and stretching in the wave propagation direction, while the shear modes consist of motion perpendicular to the propagation direction. Both the longitudinal and shear modes consist of motion perpendicular to the longitudinal direction of action.

[0083] This disclosure relates to a method of forming an acoustic resonator device and an apparatus thereby formed including a bulk acoustic wave (BAW) resonator disposed on a substrate. The BAW resonator includes a first conductive material forming a first electrode, a piezoelectric material, and a second conductive material forming a second electrode, the piezoelectric material being located between the two electrodes. An acoustic energy management structure for reducing or preventing acoustic wave dissipation into the substrate is formed on at least a portion of the active region of one surface of the BAW resonator, and an interface layer is formed on opposing surfaces of at least a portion of the active region of the BAW resonator to allow for subsequent functionalization of the active region.

[0084] According to aspects of this disclosure, acoustic wave structure devices can be fabricated using microelectromechanical systems (MEMS) techniques for producing microscale features suitable for biosensors and functionalized materials (e.g., specific binding materials). Deposition techniques such as atomic layer deposition (ALD), chemical vapor deposition (CVD), or physical vapor deposition (PVD) can be used in conjunction with one or more masks (e.g., photolithographic masks) to pattern various portions of the device being formed.

[0085] Previous methods for manufacturing BAW devices included the following steps:

[0086] 1. To manufacture a resonator having a reflective base, a bottom electrode, an inclined shear axis aluminum nitride, and a top electrode.

[0087] 2. Use tin to manufacture flip chip interconnect bumps (e.g., copper pillars).

[0088] 3. Deposit a water vapor barrier layer to protect the electrode. Examples of suitable materials are CVD Si3N4 or ALD Al2O3.

[0089] 4. Deposit a binder layer for self-assembled monolayers (SAMs) on the vapor barrier layer. Examples of suitable materials include SiO2, TiO2, or HfO2. These materials can be deposited using atomic layer deposition (ALD) or chemical vapor deposition (CVD).

[0090] 5. Mount the die onto the laminate above the slot in the board. The slot in the board defines the fluid path. Install additional components (such as switches, capacitors, and resistors) on the board to create an RF sensor module.

[0091] 6. Deposition of self-assembled monolayers (SAM). An example of a suitable material is propyltrimethoxysilane. This SAM coating is used to improve the adhesion or bonding between the SiO2 layer and the organic polymer.

[0092] 7. Print functionalized receptors (also known as biological receptors) using microarray spotting needles.

[0093] 8. Unlabeled areas of the SAM's chemical block. This prevents analytes from unintentionally adhering to the SAM when testing samples. Unbound excess chemicals are washed off the device.

[0094] 9. Manufacturing fluid packaging. An example of fluid packaging is a multi-layer stamped or laser-cut laminate with adhesive. The layers are pre-cut and machined, then applied and fixed with pressure-sensitive adhesive.

[0095] 10. The analytical material passes through the sensor cavity, where the analyte is functionalized. The resonator is driven by a sheared radio frequency to detect the frequency shift of the analyte.

[0096] Methods like these produce devices that include long electrical leads to separate the electrical bumps from the fluid channels. Furthermore, it is difficult to create a high-density resonator array with both fluid and electrical connections on the same side of the die. Flip-chip mounting of the BAW sensor, as shown above, onto a printed circuit board is one method of connecting the sensor to the board. The BAW containing the die is mounted above a slot on the board that ultimately forms the fluid channels. The thickness of the printed circuit board (PCB) determines the height of the fluid channels. Reducing the height of the fluid channels requires reducing the thickness of the PCB.

[0097] These problems are amplified when considering sensor arrays. As multiple rows of resonators are placed within the fluid path, the lead length increases. For example, if there are four resonators across the width of the fluid path, the lead length to the resonator at the center of the fluid path will be very long. This, in turn, makes it difficult to manufacture high-density resonator sensor arrays. As an example, sensor arrays can range from 2×2 (4 in total) to 50×50 (2500 in total). Even 3×3 (9 in total) arrays, which may offer a favorable trade-off between cost and performance, are difficult to manufacture using previously used methods. Currently, the thickness of commonly used PCBs is approximately 200 micrometers, thus determining the thickness of the fluid channel.

[0098] According to aspects of this disclosure, examples employ flip-chip connections with interconnect pillars for electrical and / or mechanical connection to a circuit board. Acoustic energy management structures (e.g., air cavities or acoustic mirrors) can be employed on the first side of the resonator. The opposite second side of the resonator can be exposed for use as the active portion of the sensor. The disclosed method also includes a step of removing a portion of the substrate material. The timing of this step of removing a portion of the substrate is important because if the substrate is removed too early in the process, it will be fragile and therefore difficult to handle by certain operations.

[0099] For example in Figures 1A to 1G The invention discloses a device for various stages of manufacturing according to certain methods. Figure 1A A substrate 102 having a first surface 103 and an opposing second surface 104 is described. For example, the substrate 102 may include silicon. The substrate may have various structures or layers formed on either of its surfaces and may still be used in the disclosed methods.

[0100] Figure 1BThe illustration describes a substrate 102 after a first conductive material 106 has been disposed on at least a portion of a first surface 103 of the substrate 102. The first conductive material 106, or a first electrode formed therefrom, can be described as having a first surface 105 adjacent to or closest to the substrate 102, and an opposing second surface 107 opposite the first surface 103. The step of disposing of the first conductive material can include a deposition step, a patterning step, or any combination thereof. In some embodiments, the conductive material can be deposited on at least some portions of the first surface of the substrate, or deposited on any structure or device formed on the first surface of the substrate, and then the conductive material can be patterned after one or more deposition steps. Deposition techniques such as atomic layer deposition (ALD), chemical vapor deposition (CVD), or physical vapor deposition (PVD) can be used in conjunction with one or more masks (e.g., photolithographic masks) to pattern portions of the first conductive material, and any other layers, materials, or structures discussed herein can be patterned if desired. In some embodiments, the first conductive material can include more than one material, more than one layer, or a combination thereof. In some embodiments, the first conductive material may include aluminum (Al), copper (Cu), gold (Au), platinum (Pt), combinations thereof, alloys thereof, or combinations thereof. In some embodiments, the first conductive material includes Al, its alloys, or a multilayer structure including at least one Al layer. In some embodiments, for example, the first conductive material may include Al or a bilayer structure including at least one AlCu layer and a tungsten (W) layer.

[0101] Figure 1C The diagram describes an apparatus after a piezoelectric material 110 is disposed on at least some portions of a first electrode. In some embodiments, the piezoelectric material may be deposited on all portions of the first electrode. In some embodiments, the piezoelectric material may be deposited on all portions of the first electrode that are not disposed on a first surface of a substrate or on any means or structure formed thereon. In some embodiments, a tilted c-axis hexagonal crystal structure piezoelectric material (e.g., AlN or ZnO) may be used as the piezoelectric material.

[0102] In some embodiments, the piezoelectric material may include an aluminum nitride or zinc oxide material comprising an oriented c-axis that is primarily non-parallel (and may also be non-perpendicular) to the normal to the surface of the substrate. This c-axis orientation can generate shear displacement, which advantageously enables MEMS resonator devices to operate in liquid form, for example, in sensors and / or microfluidic devices. In some embodiments, the piezoelectric material includes a c-axis with a longitudinal orientation.

[0103] A method for forming a hexagonal piezoelectric material is disclosed in U.S. Patent Application Serial No. 15 / 293,063, filed October 13, 2016, which includes a c-axis having an orientation distribution that is primarily non-parallel to the normals of the substrate surface; the aforementioned application is incorporated herein by reference. An additional method for forming a piezoelectric material having a tilted c-axis orientation is disclosed in U.S. Patent No. 4,640,756, published February 3, 1987, which is also incorporated herein by reference.

[0104] Figure 1D This describes an apparatus after a second conductive material is applied to at least a portion of a piezoelectric material. The step of applying the second conductive material may include a deposition step, a patterning step, or any combination thereof. Figure 1D As shown, in some embodiments, a conductive material may be deposited on at least some portions of the piezoelectric material, and then the conductive material may be patterned after one or more deposition steps to form a second electrode 112. The second conductive material extends substantially parallel to a first surface of the substrate. At least a portion of the second electrode 112 overlaps with the first electrode 106. The stacking of the first electrode 106, the piezoelectric material 110, and the second electrode 112 in three overlapping regions forms a bulk acoustic wave resonator 114. The bulk acoustic wave resonator 114 has a first side 112 that is parallel to a first surface 103 of the substrate 102 and furthest from the first surface 103.

[0105] Figure 1E The diagram describes an apparatus following the formation of an acoustic management structure 116 on some portions of the first side of the bulk acoustic resonator 114. The acoustic management structure may, for example, include a cavity or a reflector stack. The purpose of the acoustic management structure is to contain acoustic energy within the apparatus. A reflector stack acts as an acoustic mirror and can offer advantages in mechanical strength. A cavity can better retain energy but may also function in apparatuses with lower overall mechanical strength, or additional structures may be added to address the issue of insufficient mechanical strength.

[0106] In some embodiments, the energy management structure is an air gap or cavity. The cavity can be formed by creating two sidewalls and a "top" layer, thereby forming a cavity below the top and walls, and between the top and walls, respectively. The walls and top can be formed using a photolithographic material (e.g., a photoimageable material, such as a photoimageable epoxy resin). Specific examples of such materials may include TMMF (Tokyo Ohka Kogya Co.) or SU-8 (MicroChem Inc, Newton MA). For example, the wall and top features can have a thickness of 3 to 80 micrometers, or a thickness of 10 to 30 micrometers. The width dimension of the walls (e.g., the distance from one wall to another) can, for example, be 3 to 30 micrometers, or 5 to 15 micrometers. For example, the area of ​​the top can be 100 square micrometers to 500,000 square micrometers, or 2,500 square micrometers to 200,000 square micrometers.

[0107] In some embodiments, the acoustic energy management structure is an acoustic reflector. The acoustic reflector is used to reflect sound waves and thus reduce or avoid their dissipation in the substrate. In some embodiments, the acoustic reflector may comprise alternating layers of different materials (e.g., silicon oxycarbide [SiOC], silicon nitride [Si3N4], silicon dioxide [SiO2], aluminum nitride [AlN], tungsten [W], and molybdenum [Mo]), optionally embodied in a quarter-wave Bragg mirror. In some embodiments, other types of acoustic reflectors may also be used.

[0108] The following discussion, with regard to specific embodiments of the disclosed method, provides further details regarding feasible embodiments of the acoustic energy management structure.

[0109] Figure 1F The device following the deposition of a third conductive material 118 on a portion of the second conductive material 112 is described. It should be noted that the first, second, and third conductive materials may be the same or different. The third conductive material is deposited on the portion of the second conductive material that extends beyond the bulk acoustic wave resonator 112. In other words, the third conductive material does not cover any portion of the bulk acoustic wave resonator, but rather covers a portion of the second conductive material. The third conductive material forms an interconnect extending above the acoustic energy management structure (in a direction perpendicular to the first surface 103 of the substrate 102). The third conductive material may be described or formed as a pillar structure 118, which can be electrically connected to another device or structure in contact with it.

[0110] Figure 1GThe apparatus following the next step is described, which includes removing a portion of substrate 102 to expose a first surface 105 of the first electrode 106. The step of removing a portion of the substrate may include one or more processes. In some embodiments, removing a portion of the substrate may include mechanical and chemical treatment steps. In some embodiments, the first step of removing a portion of the substrate may remove a substantially constant thickness across the entire substrate. In some embodiments, this first step may be performed by removing additional substrate material only from certain portions of the substrate. In some embodiments, for example, a chemical removal step may follow a mechanical removal step. In some such embodiments, the first step may result in a substrate thickness of 100 micrometers to 600 micrometers, 100 micrometers to 550 micrometers, 200 micrometers to 400 micrometers, or 250 micrometers to 350 micrometers, or about 300 micrometers. An exemplary initial thickness of the substrate may be about 725 micrometers.

[0111] The step of exposing the first surface 105 of the first electrode 106 exposes the second side of the bulk acoustic wave sensor 114 for use or further processing. It should be noted that at this time, the second surface of the bulk acoustic wave resonator 114 may expose the electrode material 106 or some other layers that have been disposed on the substrate before the deposition of the first electrode material.

[0112] The additional layer that can be exposed (or even applied) at this time may include an interface layer. The interface layer can serve to allow, or more readily allow, the active surface of the bulk acoustic wave resonator 114 to be functionalized. In some embodiments, the interface layer may be patterned or otherwise made available to receive a self-assembled monolayer (SAM) over the entire active region of the bulk acoustic wave resonator, allowing the SAM and functionalized (e.g., specifically bonded) material to be applied to the interface layer to overlap the entire active region. In other embodiments, a blocking layer may be patterned on the interface layer, or only a portion of the interface layer may be available to receive the SAM over a portion of the active region, allowing the SAM and functionalized material to be applied to the interface layer to overlap only a portion of the active region.

[0113] In some embodiments, photolithography can be used to facilitate the patterning of interface or blocking materials on portions of a MEMS resonator device. Photolithography involves using light to transfer a geometric pattern from a photomask to a photosensitive chemical photoresist on a substrate and is a process well-known to those skilled in the art of semiconductor manufacturing. Typical steps employed in photolithography include wafer cleaning, photoresist application (involving positive or negative photoresist), mask alignment, and exposure and development. After features are defined in the photoresist on the desired surface, the interface layer can be patterned by etching in one or more gaps within the photoresist layer, and the photoresist layer can subsequently be removed (e.g., using a liquid photoresist stripper, ashing by applying oxygen-containing plasma, or other removal processes).

[0114] In some embodiments, the interface layer may include a hydroxylated oxide surface suitable for forming an organosilane SAM layer. A preferred interface layer material including a hydroxylated oxide surface is silicon dioxide [SiO2]. Alternative materials for forming the interface layer including a hydroxylated oxide surface include titanium dioxide [TiO2] and tantalum pentoxide [Ta2O5]. Other alternative materials including a hydroxylated oxide surface are known to those skilled in the art, and these alternatives are considered to be within the scope of this disclosure.

[0115] In other embodiments, the interface layer includes gold or another precious metal (e.g., ruthenium, rhodium, palladium, osmium, iridium, platinum, or silver) suitable for receiving thiol-based SAM.

[0116] In some embodiments involving corrosion-resistant electrode materials, an airtight layer may be applied between the top-side electrode and the interface layer. When noble metals (e.g., gold, platinum, etc.) are used for the top-side electrode, an airtight layer may not be necessary. If provided, the airtight layer preferably comprises a layer with a low water vapor permeability (e.g., not greater than 0.1 g / m³). 2 The dielectric material ( / day). After depositing these layers, a SAM (Synthetic Atom) can be formed over the interface layer, the SAM preferably comprising an organosilane material. The hermetic layer protects the reactive electrode material (e.g., aluminum or aluminum alloy) from corrosive liquid environments, and the locally patterned interface layer promotes proper chemical bonding of the SAM.

[0117] In some embodiments, the hermetic layer and / or interface layer can be applied by one or more deposition processes such as atomic layer deposition (ALD), chemical vapor deposition (CVD), or physical vapor deposition (PVD). In the aforementioned processes, ALD is preferably used to deposit at least the hermetic layer (and may also be preferred for depositing the interface layer) because it provides a superior conformal coating with good stepped coverage that is superior to device characteristics, thus providing a pinhole-free layer structure. Furthermore, ALD can form a uniform thin layer that provides relatively small acoustic vibration attenuation, which would otherwise lead to device performance degradation. Adequate coverage is important for the hermetic layer (if present) to avoid corrosion of the underlying electrodes. If ALD is used to deposit the hermetic layer, in some embodiments, the hermetic layer may include a thickness ranging from about 10 nm to about 25 nm. In some embodiments, the hermetic layer thickness is about 15 nm, or from about 12 nm to about 18 nm. Conversely, if another process such as CVD is used, the hermetic layer may include a thickness ranging from about 80 nm to about 150 nm or greater, or from about 80 nm to about 120 nm. Considering the two processes described above, the hermetic layer thickness can range from about 5 nm to about 150 nm. If ALD is used to deposit the interface layer, the interface layer can include a thickness ranging from about 5 nm to about 15 nm. In some embodiments, the interface layer can include a thickness ranging from about 10 nm, or from about 8 nm to about 12 nm. In some embodiments, other interface layer thickness ranges and / or deposition techniques besides ALD can be used. In some embodiments, the hermetic layer and interface layer can be applied sequentially in a vacuum environment, thereby promoting a high-quality interface between the two layers.

[0118] If provided, the airtight layer may include materials used as dielectrics and having low water vapor permeability (e.g., not greater than 0.1 g / m²). 2 The hermetic layer comprises an oxide, nitride, or oxynitride material. In some embodiments, the hermetic layer includes at least one of alumina (Al₂O₃) or silicon nitride (SiN). In some embodiments, the interface layer includes at least one of SiO₂, TiO₂, or Ta₂O₅. In some embodiments, multiple materials may be combined in a single hermetic layer, and / or the hermetic layer may include multiple sublayers of different materials. Preferably, the hermetic layer is further selected to promote compatibility with the reactive metal (e.g., aluminum or aluminum alloy) electrode structure beneath the acoustic resonator structure. Although aluminum or aluminum alloys are frequently used as electrode materials in bulk acoustic resonators, various transition and post-transition metals can be used for such electrodes.

[0119] Following the deposition of the interface layer (optionally disposed on the underlying hermetic layer), a SAM is preferably formed on the interface layer. SAMs are typically formed by exposing a solid surface to amphiphilic molecules having chemical groups that exhibit a strong affinity for the solid surface. When using an interface layer comprising a hydroxylated oxide surface, organosilane SAMs are particularly preferred for attachment to the hydroxylated oxide surface. Organosilane SAMs promote surface bonding via silicon-oxygen (Si-O) bonds. More specifically, organosilane molecules include hydrolysis-sensitive groups and organic groups, and can therefore be used to couple inorganic materials to organic polymers. Organosilane SAMs can be formed by exposing the hydroxylated oxide surface to the organosilane material in the presence of trace amounts of water to form intermediate silanol groups. These groups then react with free hydroxyl groups on the hydroxylated surface to covalently fix the organosilane. Examples of possible organosilane-based SAMs compatible with interface layers comprising hydroxylated oxide surfaces include 3-glycidoxypropyltrimethoxysilane (GPTMS), 3-mercaptopropyltrimethoxysilane (MPTMS), 3-aminopropyltrimethoxysilane (APTMS), and octadecyltrimethoxysilane (OTMS), including their ethoxy- and chloro-variants. Other silanes that can be used in SAMs include poly(ethylene glycol) (PEG) conjugated variants. Those skilled in the art will recognize that other alternatives exist and are considered to be within the scope of this disclosure. Exemplary SAMs may comprise a thickness of at least 0.5 nm or greater. Preferably, the SAM readily bonds to a locally patterned interface layer but not readily bonds to other adjacent material layers (e.g., hermetic layers, piezoelectric materials, and / or barrier material layers).

[0120] When using an interface layer containing gold or another noble metal, thiol-based (e.g., alkathiol-based) SAM layers can be used. Alkathiols are molecules having an alkyl chain as the backbone, a tail group, and an SH head group. Due to the strong affinity of sulfur for these metals, thiols can be used in noble metal interface layers. Examples of thiol-based SAMs that can be used include, but are not limited to, 1-dodecanethiol (DDT), 11-mercaptoundecanoic acid (MUA), and hydroxyl-terminated (hexaethylene glycol)undecanethiol (1-UDT). These thiols contain the same backbone but different end groups—namely, methyl (CH3), carboxyl (COOH), and hydroxyl-terminated hexaethylene glycol (HO-(CH2CH2O)6) for DDT, MUA, and 1-UDT, respectively. In some embodiments, the SAM can be formed by incubating the gold surface in a thiol solution using a suitable solvent (e.g., anhydrous ethanol).

[0121] After the formation of the SAM, the SAM can be biologically functionalized, for example by accepting at least one functionalized (e.g., specifically bound) material. In some embodiments, the specifically bound material can be applied to or over the SAM using microarray spotting needles or other suitable methods. Because the SAM and the underlying interface layer are patterned with high dimensional tolerances only on a portion of the resonator structure (including the substrate) (e.g., using photolithography to define the interface layer), and the subsequently applied specifically bound material preferably adheres only to the SAM, higher dimensional tolerances can be achieved in the positioning of the specifically bound material compared to individual microarray spotting.

[0122] Figure 1H The apparatus after additional processing is described. For example, Figure 1H The device has been flipped over and then placed on the second substrate 120 for electrical connection, for example, with other devices. The device is electrically connected to the second substrate 120, which may be, for example, a printed circuit board (PCB). For example, the second substrate 120 may be connected to the device via electrical contact pads 122. Figure 1H The apparatus also includes a fluid wall 122 formed on the second substrate 120. The fluid wall can be formed of any suitable material, such as a laser-cut "template" layer of a thin polymeric material and / or laminate, optionally including one or more self-adhesive surfaces (e.g., adhesive tape). Alternatively, such a wall can be formed with SU-8 negative epoxy resist or other photoresist materials prior to the deposition of the SAM layer, functionalized layer, and / or blocking layer. Figure 1H The device also includes a capping layer 124 or a cover layer. The capping layer 124 can be formed by defining a port in a suitable material layer (e.g., preferably a substantially inert polymer, glass, silicon, ceramic, etc.) (e.g., by laser cutting or waterjet cutting) and adhering the capping layer or cover layer to the top surface of the fluid wall 122. The combination of the capping layer 124 and the fluid wall 122 forms a fluid channel 126.

[0123] Figure 1I The functionalized device is described, denoted by YYYY, and blocking is denoted by XXXXX. Examples of specific binding materials used for functionalization include, but are not limited to, antibodies, receptors, ligands, etc. The specific binding material is preferably configured to receive a predetermined target substance (e.g., molecules, proteins, DNA, viruses, bacteria, etc.). The functionalized layer including the specific binding material may include a thickness in the range of about 5 nm to about 1000 nm, or about 5 nm to about 500 nm. In some embodiments, arrays of different specific binding materials may be provided on different active regions of a multi-resonator device (i.e., a resonator device including multiple active regions), optionally combined with one or more active regions without specific binding material to serve as comparison (or "reference") regions. In some embodiments, the functionalized material may provide the utility of non-specific binding.

[0124] Figure 1J An alternative to the step of forming the fluid wall to which the cap 124 is attached is provided. In this embodiment, the cap 124 is directly attached to the electrode material forming the channel 128.

[0125] Figures 2 to 20 A more specific method for forming a fluid device including a bulk acoustic resonator according to an example of this disclosure is described. Typically, deposition techniques such as atomic layer deposition (ALD), chemical vapor deposition (CVD), or physical vapor deposition (PVD), or other techniques, can be used to deposit materials. One or more masks (e.g., photolithographic masks), stop layers, etched layers, etc., can also be used to pattern portions of any material deposited herein to form the layer or structure shown. Although Figures 2 to 20 The diagram illustrates the formation of a three-resonator structure, the associated electrical connections, and the structural methods. For clarity, only one of the repeating structures is typically provided with reference numerals.

[0126] Figure 2 A substrate 200 having a first surface 201 and a second surface 202 is generally described. A sacrificial layer 203 has been formed on a portion of the first surface 201. When the second side 202 of the substrate 200 is partially removed, the sacrificial layer can protect the resonator device formed by the method. The substrate can be, for example, a silicon substrate and the sacrificial material can be, for example, aluminum. The sacrificial layer is typically deposited and patterned in the region where the resonator will be formed.

[0127] Figure 3 The structure following a step aimed at forming a flat surface for further process steps is described. Specifically, additional silicon oxide material can be deposited onto the sacrificial material 202 and the exposed portion of the first surface 201 of the substrate 200. The deposition of the silicon oxide material can be followed by a chemical mechanical polishing (CMP) process, for example, to form a planar silicon oxide layer 204, the top surface of which is flush with the sacrificial layer 203. In other words, the top surface of the silicon oxide layer 204 is flush with... Figure 2 The top surface of the patterned sacrificial layer 202 deposited in the illustrated step is flush with the surface. The silicon oxide layer 204, the sacrificial layer, or both can be used not only as a planarization layer on which additional structures are formed, but also as a silicon etch stop layer, a functionalized bonding surface, or as a silicon etch stop layer and a functionalized bonding surface in steps of the subsequently disclosed process. Optionally, if the silicon oxide material has a greater thickness, it can also provide some temperature compensation properties. For example, a silicon oxide material with a thickness of at least 300 nanometers can contribute to temperature compensation of the device. For example, the specific thickness of the silicon oxide material can, at least in part, depend on the operating frequency of the device, the materials in the device, the thickness of various materials in the device, or a combination thereof.

[0128] Figure 4 The structure after forming a passivation layer 206 on the sacrificial layer 202 and the silicon oxide layer 204 is illustrated. The passivation layer 206 can, for example, function as a moisture barrier. For example, the illustrative passivation layer may include silicon nitride and aluminum oxide (e.g., AlO deposited by ALD). The passivation layer can provide moisture protection properties that can be used to protect the device.

[0129] Figure 5 The structure after the sacrificial layer 202 has been removed is illustrated. For example, the sacrificial layer 202 can be removed by etching it from the non-substrate side of the structure to form the resonator gap 208. In some specific embodiments, a photoresist pattern can be applied and holes (not shown) can be etched through the passivation layer 206 overlaid on the sacrificial layer 202. Illustrative etchants that can be used with this particular set of materials may include “16-1-1-2,” which refers to a composition containing, by volume, 16 parts H3PO4: 1 part HNO3: 1 part CH3COOH: 2 parts H2O, which does not etch silicon nitride or silicon but does etch aluminum oxide. If other materials are used for the passivation layer 206 and the sacrificial layer 202, those skilled in the art will know of feasible etchant compositions. The formation of the resonator gap 208 allows the final resonator to be probed and trimmed for final use.

[0130] Figure 6 The structure following the formation of the first electrode 210 is illustrated. The formation or deposition of the first electrode 210 may include material deposition, material patterning, or any combination thereof. Silicon oxide material 212 is then deposited on the structure and (e.g., using CMP) planarized to form a flat surface for subsequent process steps. Suitable conductive materials for the first electrode, for example, may include aluminum, an aluminum-copper alloy, tungsten, or combinations thereof.

[0131] Figure 7 The structure following the deposition of piezoelectric material 214 on the exposed surface of silicon oxide material 212 is illustrated. An example of a suitable material for the tilted shear-axis piezoelectric film is aluminum nitride, which can be deposited at an angle different from that perpendicular to the substrate. An optional tilted piezoelectric seed layer can also be used before depositing the bulk piezoelectric material. The tilted shear-axis piezoelectric film can consist of an aluminum nitride seed layer deposited at an angle and an aluminum nitride bulk piezoelectric film deposited perpendicular to the substrate. The tilted seed layer can promote the tilting of the microstructure of the bulk shear film, thereby providing shear piezoelectric properties.

[0132] Figure 8The apparatus following the formation or deposition of a second electrode 216 on a piezoelectric layer 214 is described. The formation of the second electrode 216 may include material deposition, material patterning, or any combination thereof. For example, a suitable conductive material for the first electrode may include aluminum, an aluminum-copper alloy, tungsten, or a combination of these materials. The material of the second electrode 216 may be the same as or different from the material of the first electrode 210. One or more overlapping regions of the first electrode 210, the piezoelectric layer 214, and the second electrode 216 form a bulk acoustic resonator 220.

[0133] Figure 9 The device after the formation of the deposited layer 222 is described. The deposited layer is an optional structure that can lead to a reduction in parasitic losses along the length of the lead extending from the second electrode. Some examples of suitable deposited materials include aluminum, aluminum-copper alloys, tungsten, or combinations of these metals.

[0134] Figure 10 The device following the formation of the second passivation layer 224 is described. The second passivation layer 224 may include the materials described with respect to the first passivation layer and may provide the same or similar functionality as the first passivation layer. The materials, properties, and characteristics (e.g., thickness, etc.) may be the same as or different from the first passivation layer. The second passivation layer may not be deposited in an active region (e.g., above the bulk acoustic resonator 220), or may not be present in an active region, or may be deposited on a second electrode that will form an interconnect, as further described below.

[0135] Figure 11 The device following the formation of the acoustic energy management structure 226 is illustrated. In this example, the acoustic energy management structure 226 is an air cavity. Because the acoustic energy management structure covers the resonator, it also provides protection against contact with and damping of the resonator by materials, chemicals, or both. Materials that can be used to manufacture the acoustic energy management structure may include photoresists or photoimageable epoxy resins, such as TMMF (Tokyo Ohka Kogya Co.) or SU-8 (MicroChem Inc, Newton MA). The acoustic energy management structure including the air cavity 226 can be manufactured, for example, as a two-layer structure, such as a wall layer and a top layer.

[0136] Figure 12The device following the next step describes forming interconnects 228 disposed on at least a portion of the second electrode material in a region that does not overlap with the bulk acoustic resonator 220. The interconnects 228 provide electrical, mechanical, or a combination thereof, connections between the acoustic resonator 220 and another structure or device. The interconnects can be formed as electrical interconnect bumps. For example, the interconnects can be formed from tin-containing copper pillars. Fabricating copper-plated leads with tin may include patterning the region using a photoresist, depositing an optional electroplating seed layer (e.g., titanium and copper), electroplating the interconnects, and then removing the optional electroplating seed layer and photoresist.

[0137] Figure 13 The apparatus is described after a portion of the second surface 202 of the substrate has been removed to expose the modified second surface 230. This step can be accomplished by a thinning or non-selective site removal step (e.g., a process such as back-side grinding). Back-side grinding provides the desired substrate thickness. In some examples, such as where the final microfluidic channel height will be defined by the distance from the back surface 230 to the top of the separately formed wall (see later process steps), substrate thickness is important. The fluid channels are further described below. In some alternative embodiments, the substrate can be thinned earlier, and then a temporary carrier can be used to provide mechanical stability for some processing steps.

[0138] Figure 14A The structure after selectively removing a portion of the substrate from the modified second surface 230 to form the top substrate surface 233 is described. Specifically, the area of ​​substrate removed is the region located below the acoustic resonator 220. Alternatively, material extending beyond the periphery of the acoustic resonator 220 may also be removed. Once the substrate material is removed, the hermetic layer (e.g., silicon nitride) and the interface layer (e.g., silicon oxide) are exposed.

[0139] In embodiments where the sacrificial layer was not removed previously, it can be removed at this point. This is due to... Figure 14AThe apparatus is described in the diagram. If the sacrificial layer remains intact for substrate removal, it can be used to protect the electrodes during backside dry etching. A specific process for completing this selective removal of a portion of the substrate involves dry silicon etching over the area of ​​resonator 220. A specific illustrative method for completing this process is to coat the backside of the wafer with photoresist; typically, for dry etching, this is a thick photoresist layer of 5 to 10 micrometers. A backside alignment tool aligns with the frontside alignment marks and exposes the photoresist. The photoresist can be developed, and silicon can be etched by alternating deep reactive ion etching (DRIE) of silicon with sulfur hexafluoride (SF6) and octafluorocyclobutane (C4F8) passivation layers. Another masking process for the photoresist involves depositing aluminum on the backside and opening the pattern by laser processing. Another useful silicon etching process may include anisotropic wet chemical etching using potassium hydroxide (KOH) or tetramethylammonium hydroxide (TMAH) to selectively remove the substrate along the active region. In this case, the wall profile would be 54.7 degrees, for example, along the <111> plane of silicon in the substrate.

[0140] Figure 14B The apparatus as seen from the second surface 202 of the substrate 200 is described. Figure 14B It is an acoustic resonator 220 and a groove 235 formed to expose the acoustic resonator 220. Figure 14C The device is shown as viewed from the first surface 201 of the substrate 200. From this surface, acoustic energy management structures, such as air chambers 226 and pillars 228, can be seen.

[0141] Figure 15A The arrangement after flip-chip mounting to sensor board 240 is described. In one example, interconnects, pillars 228, are electrically connected, for example, by soldering them to copper pads 242 with an organic solderability protectant (OSP). Another alternative may include soldering solder balls on the die to bonding pads. For example, the bonding pads may be formed of a suitable conductive material such as gold. There is no fluid on the chip side with interconnect bumps.

[0142] Figure 15B Explanation Figure 15A The cross-section of the device is shown, as are the sensor plate 240 and the substrate 200. Figure 15C The structure of the second surface 202 from the substrate 200 is shown, and the trench 235 exposing the acoustic resonator 220 is shown.

[0143] Figure 15D A diagram illustrating the bottom surface 241 of the sensor board is shown. The positions of the support column 228, the air cavity 226, and the acoustic resonator 220 are also shown. Figure 15EAn illustration of the top surface 243 of the sensor board is shown. The respective locations of the remaining substrate 200 and the acoustic resonator 220 are also shown. Finally, region 245 shows the substrate being etched to the depth exposing the first electrode layer 210 of the acoustic resonator 220, thus forming the bottom of the fluid channel.

[0144] Figure 16 Article 19 describes a method for forming fluid channels with independent walls. Figure 16 An apparatus is shown after the fluid wall structure 250 has been formed or attached to the sensor plate 240. In some illustrative embodiments, the fluid wall structure 250 may be attached to the sensor plate 240 using an adhesive 252. The fluid wall structure may be formed by injection molding of plastic, machining of metal or glass, or other suitable methods. In mass production, an automated robotic system may be used to dispense the adhesive at the location of the fluid wall structure. The wall structure may be received on the adhesive in the form of a tape measure or reel or a tray. The wall structure may be positioned on the adhesive. The adhesive is cured in an oven. The fluid wall structure is configured to accommodate a desired fluid channel height from the resonator to the top of the wall. The final fluid channel height 254 can be described as from the surface of the first electrode 210 to the top of the fluid wall structure 250.

[0145] Figure 17A This illustrates the structure following the deposition of underfill adhesive 256 beneath the flip-chip mounted die. Figure 17B The first cross-section of the structure is shown, and the bottom filler adhesive 256 is depicted. Figure 17C An isometric view of the structure is shown, along with the underfill adhesive 256. Adhesive from the dispenser tip can be placed near the side of the die. Capillary forces can draw away the adhesive under the mounted die. A baking step can then be performed to cure the adhesive. The baking step can be completed to cure both the underfill adhesive and the fluid wall structure adhesive. The purpose of the underfill adhesive is to protect the raised areas of the die from chemical corrosion by the fluids used when operating the sensor.

[0146] Figure 18 This explains the functionalization ( Figure 18 (represented as YYY) and blocking ( Figure 18 The structure following (represented as XXXXXX) in the middle. Figure 18 The functionalization chemistry on the sensor is explained. First, a silanization step can be performed to coat a monolayer of adhesion promoter onto the surface. Then, the functionalization can be printed onto the resonator, and finally, the unfunctionalized surface is blocked to prevent non-specific binding. The functionalization can be a biological receptor designed to bind analytes of interest. For example, the functionalization can be a protein.

[0147] Figure 19A and 19B(Cross-section) illustrates the structure after the fluid channel cover 260 is attached to the fluid wall structure 250. Figure 19A and 19C The structure also shows a fluid inlet 262 and a fluid outlet 264. Examples of suitable fluid chamber covers could be tape or adhesive. The cover can be stamped or laser-machined according to its size and the inlet and outlet ports. For example, the cover can be attached in place by pressure.

[0148] Figure 20 Explanation Figure 16 Alternative methods for forming fluid channels up to 19. Figure 20 In this embodiment, the fluid chamber cap 260 is attached to the mounted flip chip and underfill adhesive 256 substrate (220) / sensor board (240) structure. In this embodiment, the fluid chamber cap 260 can be directly attached to the top substrate surface 233. In this embodiment, the fluid chamber cap 260 can be tape or adhesive. The fluid chamber cap 260 can be stamped or laser-processed to suit the size and forming of the inlet and outlet ports. For example, the fluid chamber cap 260 can be pressure-attached into place.

[0149] In this figure, the resonator is observed within etched trenches in the substrate. Additionally, the end region of the die can be etched to create space for inlet and outlet fluid ports. The etched silicon portion of the substrate serves to provide a channel for fluid flowing near the resonator. To complete sensor testing, fluid can flow into the fluid inlet in the cap, then through the resonator and out through the fluid outlet. The etched silicon portion of the substrate serves to provide a channel for fluid flowing near the resonator. Analytes of interest can be combined with functionalized chemicals and cause changes in the amplitude-volume characteristics of the bulk acoustic wafer device.

[0150] Figures 21 to 36 This paper describes another illustrative method for manufacturing a fluid device comprising a bulk acoustic resonator and a mirror as a sound wave management structure. Those skilled in the art will understand that the above-described manufacturing process (e.g., from...) Figures 2 to 10 The shown diagram can also be used with this method to form a structure that includes a device that includes an alternative reflector.

[0151] Figure 21 This describes a substrate such as silicon, on which silicon oxide and silicon nitride are deposited. The silicon oxide acts as a silicon etch stop layer and a functional bonding surface for the device. Furthermore, a thicker silicon oxide layer can serve as a temperature compensation layer for the device. The silicon nitride layer is a moisture-proof layer protecting the device.

[0152] Figure 22 The process involves adding electrode material and silicon oxide, followed by a CMP process to planarize the surface. Suitable electrode materials may include aluminum, aluminum-copper alloys, tungsten, or combinations of these metals.

[0153] Figure 23 The deposition of piezoelectric films (e.g., tilted shear-axis piezoelectric films) is described. Suitable materials may include aluminum nitride. Shear-axis films may include a seed layer to promote tilting of the bulk shear film.

[0154] Figure 24 This illustrates the deposition and patterning of electrodes on a piezoelectric material. Suitable electrode materials include aluminum, aluminum-copper alloys, tungsten, or combinations of these metals. A resonator is formed where the two electrodes overlap with the piezoelectric material.

[0155] Figure 25 The deposition and patterning of the packing layers are explained. The purpose of the packing layers is to reduce parasitic losses along the lead length. Suitable packing materials include aluminum, aluminum-copper alloys, tungsten, or combinations of these metals.

[0156] Figure 26 This illustrates the deposition and patterning of the protective layer. A suitable protective layer is silicon nitride. The protective layer is not deposited in the active region or at locations where copper pillars will form.

[0157] Figure 27 The deposition and patterning of acoustic reflectors in the resonator region are illustrated. The purpose of acoustic reflectors is to return acoustic energy to the resonator to improve device performance. Acoustic reflectors can be fabricated using alternating layers of silicon oxide and patterned tungsten, or alternating layers of silicon oxide and aluminum nitride.

[0158] Figure 28 The fabrication of electrical interconnect bumps is described. Suitable materials include copper pillars with tin. Fabricating electroplated copper leads with tin involves patterning an area using a photoresist, depositing a plating seed layer (e.g., titanium and copper), plating the interconnect bumps, and then removing the plating seed layer and photoresist.

[0159] Figure 29 The apparatus is illustrated after the substrate has undergone back-side grinding. The purpose of back-side grinding is to achieve the desired substrate thickness. In the case of independent wall fluid, the substrate thickness will define the height of the fluid channel adjacent to the resonator sensor. In the case of etched die substrate fluid, the substrate thickness will define the channel height of the fluid channel. The following figures will illustrate this.

[0160] Figure 30This describes the device after the substrate has been dry-etched into the resonator region. One method to accomplish this process is to apply a photoresist to the back of the wafer; typically, for dry etching, this is a thick photoresist of about 5 to 10 micrometers. A back-side alignment tool aligned with the front-side alignment mark is used to expose the photoresist. The photoresist is then developed. The straight sidewalls are etched by alternating deep reactive ion etching (DRIE) of silicon with SF6 and C4F8 passivation layers. Another masking process for the photoresist involves depositing aluminum on the back side and opening the pattern using laser processing.

[0161] Figure 31 This describes the setup after the flip chip is mounted on the board. One interconnect embodiment involves soldering tin-coated copper pillars on the die to copper pads coated with an organic solderability protectant (OSP). Alternatively, solder balls on the die are soldered to gold bonding pads.

[0162] Figures 32 to 36 illustrate examples of fluid channels defined by separate walls. Figure 32A This describes the attachment of a fluid wall to a plate. The fluid wall structure can be formed through injection molding of plastics, or by processing metal or glass. In mass production, a robot dispenses adhesive at the location of the fluid wall structure. In mass production, the wall structure is received in the form of a tape measure, reel, or pallet. The robot places the wall structure onto the adhesive. The adhesive is cured in an oven. The fluid wall structure is designed to achieve the desired fluid channel height from the resonator to the top of the wall. There is no fluid on the die side with interconnecting bumps. The fluid wall structure is not shown in dimensions; in reality, the wall width will be quite wide to allow for the engagement of the fluid cap. Figure 32B A plan view of the die side and intendent wall structure opposite the interconnect bumps is shown. The resonator can be observed in the etched portion of the substrate in this figure. The cover strip is not shown, but a schematic diagram of the inlet and outlet openings in the cover is shown. For sensor testing, fluid flows through the die with the resonator into the fluid inlet and out the fluid outlet. The etched silicon portion of the substrate provides a channel for the fluid flowing near the resonator.

[0163] Figure 33 This describes the underfill adhesive applied beneath the flip-chip mounted die. Adhesive from the dispensing tip is placed near the side of the die. Capillary forces absorb the adhesive under the mounted die. A final step is performed to cure the adhesive. The purpose of the underfill adhesive is to protect the raised areas of the die from the chemical corrosion of the fluids used when operating the sensor.

[0164] Figure 34The functionalization chemistry on a biosensor is described. First, a silanization step is performed to coat a monolayer of adhesion promoter onto the surface. Then, the functionalization is printed onto the resonator, and subsequently, the surface is blocked to prevent non-specific binding. Functionalization is a biological receptor designed to bind an analyte of interest. For example, the functionalization could be a protein.

[0165] Figure 35 This describes the device after the fluid chamber cover has been attached. Examples of suitable fluid chamber covers are tape or adhesive labels. The cover is stamped or laser-machined according to its size and the inlet and outlet ports. The cover is attached in place by pressure. Figure 35 This describes the assembly after the fluid chamber cap has been attached to the BAW die. Examples of suitable fluid chamber caps are tape or adhesive. The cap is stamped or laser-machined according to size and inlet and outlet ports. The cap is attached in place by pressure.

[0166] Figure 36 A plan view of the die side opposite the interconnect bumps is shown. In this figure, the resonator is observed in an etched portion of the substrate, with the end region of the die also etched to make room for inlet and outlet fluid ports. The etched silicon portion of the substrate provides a channel for fluid flowing near the resonator. To complete sensor testing, fluid flows into the fluid inlet in the cap, then through the resonator and out through the fluid outlet. The etched silicon portion of the substrate provides a channel for fluid flowing near the resonator. The analyte of interest combines with functionalized chemicals and causes changes in the amplitude-volume characteristics of the bulk acoustic wafer device.

[0167] Figures 32 to 36 illustrate examples of fluid channels defined by separate walls. Figure 37 It is an alternative method to these process steps. In Figure 37 In this embodiment, the fluid chamber cap 260 is attached to the mounted flip chip and underfill adhesive 256 substrate (220) / sensor board (240) structure. In this embodiment, the fluid chamber cap 260 can be directly attached to the top substrate surface 233. In this embodiment, the fluid chamber cap 260 can be tape or adhesive. The fluid chamber cap 260 can be stamped or laser-processed to suit the size and forming of the inlet and outlet ports. For example, the fluid chamber cap 260 can be pressure-attached into place.

[0168] In this figure, the resonator is observed within etched trenches in the substrate. Additionally, the end region of the die can be etched to create space for inlet and outlet fluid ports. The etched silicon portion of the substrate serves to provide a channel for fluid flowing near the resonator. To complete sensor testing, fluid can flow into the fluid inlet in the cap, then through the resonator and out through the fluid outlet. The etched silicon portion of the substrate serves to provide a channel for fluid flowing near the resonator. Analytes of interest can be combined with functionalized chemicals and cause changes in the amplitude-volume characteristics of the bulk acoustic wafer device.

[0169] Figures 38 to 54 This illustrates another example method for manufacturing a fluid device that includes a bulk acoustic resonator. Figure 38 This describes a silicon-on-insulator (SOI) wafer substrate. Those skilled in the art will understand that any part of the manufacturing process described above can also be used in this method.

[0170] Figure 39 This illustrates the patterning of hard masks such as silicon dioxide or silicon nitride, and the anisotropic wet etching of the top silicon. Wet etching can be performed using TMAH or KOH. Figure 40 This describes the removal of the silicon oxide hard mask through wet etching and the deposition of the silicon nitride layer. The silicon nitride layer serves as a moisture barrier to protect the device. Figure 41 The addition of electrodes is described. Suitable electrode materials include aluminum, aluminum-copper alloys, tungsten, or combinations of these metals. Figure 42 The deposition of a tilted shear axis piezoelectric film is illustrated. A suitable material is aluminum nitride. The shear axis film may include a seed layer to promote the tilting of the bulk shear film. Figure 43 This illustrates the deposition and patterning of electrodes on a piezoelectric material. Suitable electrode materials include aluminum, aluminum-copper alloys, tungsten, or combinations of these metals. A resonator is formed where the two electrodes overlap with the piezoelectric material. Figure 44 The deposition and patterning of the packing layers are explained. The purpose of the packing layers is to reduce parasitic losses along the lead length. Suitable packing materials include aluminum, aluminum-copper alloys, tungsten, or combinations of these metals. Figure 45 The fabrication of the protective cavity for the resonator is described. The purpose of the protective cavity is to prevent material contact and dampen the resonator. Suitable materials for fabricating the cavity include optically imageable TMMF. This can be done in two layers: a wall layer and a top layer. Figure 46 This describes the fabrication of electrical interconnect bumps. Suitable materials include copper pillars with tin. Fabricating electroplated copper leads with tin involves patterning areas using a photoresist, depositing a plating seed layer (such as titanium and copper), plating the interconnect bumps, and then removing the plating seed layer and photoresist. Figure 47 The diagram illustrates the device after the substrate has been removed. Thinning or removal processes can be performed by etching silicon using dry etching (SF6) or wet etching (TMAH). Alternatively, the wafer can be used as a background for substrate removal.

[0171] Figure 48 This describes the setup after the flip chip is mounted on the board. One interconnect embodiment involves soldering tin-coated copper pillars on the die to copper pads coated with an organic solderability protectant (OSP). Another option is to solder solder balls on the die to gold bonding pads.

[0172] Figure 49A This describes the attachment of a fluid wall to a plate. The fluid wall structure can be formed through injection molding of plastics, or by processing metal or glass. In mass production, a robot dispenses adhesive at the location of the fluid wall structure. In mass production, the wall structure is received in the form of a tape measure, reel, or pallet. The robot places the wall structure onto the adhesive. The adhesive is cured in an oven. The fluid wall structure is designed to achieve the desired fluid channel height from the resonator to the top of the wall. Figure 49B This diagram illustrates a plan view of the side of a flip-chip BAW sensor die mounted on a board, along with a representation of the independent wall structure. The die side with interconnect bumps is free of fluid. The fluid wall structure is not shown in dimensions; in reality, the wall width would be wide enough to allow for the engagement of the fluid cap.

[0173] Figure 50 This describes the underfill adhesive applied beneath the flip-chip mounted die. Adhesive from the dispensing tip is placed near the side of the die. Capillary forces absorb the adhesive under the mounted die. A final step is performed to cure the adhesive. The purpose of the underfill adhesive is to protect the raised areas of the die from the chemical corrosion of the fluids used when operating the sensor.

[0174] Figure 51 The functionalization chemistry on a biosensor is described. First, a silanization step is performed to coat a monolayer of adhesion promoter onto the surface. Then, the functionalization is printed onto the resonator, and subsequently, the surface is blocked to prevent non-specific binding. Functionalization is a biological receptor designed to bind an analyte of interest. For example, the functionalization could be a protein.

[0175] Figure 52A This describes the device after the fluid chamber cover has been attached. Examples of suitable fluid chamber covers are tape or adhesive labels. The cover is stamped or laser-machined according to its size and the inlet and outlet ports. The cover is attached in place by pressure. Figure 52B A plan view of the die side and independent wall structure opposite the interconnect bumps is shown. The resonator is observed in an etched portion of the substrate in this figure. The cover strip is not shown, but a schematic diagram of the inlet and outlet openings in the cover is shown. For sensor testing, fluid flows through the die with the resonator into the fluid inlet and out the fluid outlet. The etched silicon portion of the substrate serves to provide a channel for the fluid flowing near the resonator.

[0176] Figures 38 to 44The described process can be achieved by using... Figures 53 to 62 The demonstrated process steps complete the formation of a reflector that includes a resonator, replacing the original structure. Figures 38 to 44 A device that forms an air cavity. (Completed) Figures 38-44 The process steps are performed, and then the structure has the following characteristics: Figures 53 to 62 The acoustic reflector formed thereon is shown. Similarly, Figures 38 to 4 Processes 53 to 62 illustrate another example method for fabricating a fluid device including a bulk acoustic resonator. According to this example, the fluid device includes an etched silicon-on-insulator (SOI) wafer and an acoustic reflector. Those skilled in the art will understand that the above-described fabrication processes can also be used in conjunction with this method.

[0177] Figure 53 The diagram illustrates the device after fabricating an acoustic reflector on the resonator. The purpose of the acoustic reflector is to return acoustic energy to the resonator to improve the device's performance. The acoustic reflector can be fabricated using alternating layers of silicon oxide and patterned tungsten, or alternating layers of silicon oxide and aluminum nitride.

[0178] Figure 54 This describes the fabrication of electrical interconnect bumps. Suitable materials include copper pillars with tin. Fabricating electroplated copper leads with tin involves patterning the area using a photoresist, depositing a plating seed layer (such as titanium and copper), plating the interconnect bumps, and then removing the plating seed layer and photoresist.

[0179] Figure 55 The apparatus after substrate removal is shown. Thinning or removal processes can be performed by etching silicon using dry etching (SF6) or wet etching (TMAH). Alternatively, the wafer can be used as a background for substrate removal.

[0180] Figure 56 This describes the device after the flip chip is mounted on the board. One interconnect embodiment involves soldering tin-coated copper pillars on the die to copper pads coated with an organic solderability protectant (OSP). Another option is to solder solder balls on the die to gold bonding pads.

[0181] Figure 57 This describes the attachment of a fluid wall to a plate. The fluid wall structure can be formed through injection molding of plastics, or by processing metal or glass. In mass production, a robot dispenses adhesive at the location of the fluid wall structure. In mass production, the wall structure is received in the form of a tape measure, reel, or pallet. The robot places the wall structure onto the adhesive. The adhesive is cured in an oven. The fluid wall structure is designed to achieve the desired fluid channel height from the resonator to the top of the wall.

[0182] Figure 58This describes the underfill adhesive applied beneath the flip-chip mounted die. Adhesive from the dispensing tip is placed near the side of the die. Capillary forces absorb the adhesive under the mounted die. A final step is performed to cure the adhesive. The purpose of the underfill adhesive is to protect the raised areas of the die from the chemical corrosion of the fluids used when operating the sensor.

[0183] Figure 59 The functionalization chemistry on a biosensor is described. First, a silanization step is performed to coat a monolayer of adhesion promoter onto the surface. Then, the functionalization is printed onto the resonator, and subsequently, the surface is blocked to prevent non-specific binding. Functionalization is a biological receptor designed to bind an analyte of interest. For example, the functionalization could be a protein.

[0184] Figure 60 This describes the device after the fluid chamber cover has been attached. Examples of suitable fluid chamber covers are tape or adhesive labels. The cover is stamped or laser-machined according to its size and the inlet and outlet ports. The cover is attached in place by pressure.

[0185] Figure 61 This diagram illustrates a plan view of the side of a flip-chip BAW sensor die mounted on a board, along with a representation of the independent wall structure. The die side with interconnect bumps is free of fluid. The fluid wall structure is not shown in dimensions; in reality, the wall width would be wide enough to allow for the engagement of the fluid cap.

[0186] Figure 62 A plan view of the die side and intended wall structure opposite the interconnect bumps is shown. The resonator can be observed in the etched portion of the substrate in this figure. The cover strip is not shown, but a schematic diagram of the inlet and outlet openings in the cover is shown. For sensor testing, fluid flows through the die with the resonator into the fluid inlet and out the fluid outlet. The etched silicon portion of the substrate serves to provide a channel for the fluid flowing near the resonator.

[0187] It should be understood that the various aspects disclosed herein can be combined in combinations different from those specifically presented in the specification and drawings. It should also be understood that, by way of example, certain actions or events of any process or method described herein may be performed in a different order, may be added, combined, or may be omitted entirely (e.g., all described actions or events may not be necessary to perform these techniques). The invention is defined in the claims. However, a non-exhaustive list of non-limiting examples is provided below. Any one or more features of these examples may be combined with any one or more features of another example, embodiment, or aspect described herein.

[0188] Example 1 is a method of manufacturing a bulk acoustic wave resonator structure for a fluid device, comprising: disposing a first conductive material over a portion of a first surface of a substrate to form at least a portion of a first electrode, the substrate having a second surface opposite to the first surface; disposing a piezoelectric material over the first electrode; disposing a second conductive material over the piezoelectric material to form at least a portion of a second electrode, wherein the second conductive material extends substantially parallel to the first surface of the substrate and extends at least partially over the first conductive material, wherein the overlapping region of the first conductive material, the piezoelectric material, and the second conductive material forms a bulk acoustic wave resonator having a first side and an opposing second side; disposing an acoustic energy management structure over the first side of the bulk acoustic wave resonator; disposing a third conductive material over the extension of the second conductive material beyond a portion of the bulk acoustic wave resonator, wherein the third conductive material forms an interconnect extending over the acoustic energy management structure in a direction substantially perpendicular to the first surface of the substrate; and removing a portion of the second surface of the substrate to expose a chemical mechanical connection at the first electrode on the second side of the bulk acoustic wave resonator.

[0189] Example 2 is the method of Example 1, wherein the reflector structure is disposed above a first side of the bulk acoustic resonator, including walls and tops formed of photoresist material to define a protective cavity above the bulk acoustic resonator.

[0190] Example 3 is a method of Example 1, wherein forming a reflector structure above a first side of a bulk acoustic resonator includes setting a material layer to form an acoustic reflector above the bulk acoustic resonator.

[0191] Example 4 is a method of Example 1, further comprising: setting and patterning a sacrificial layer on a substrate; and setting a passivation layer over the sacrificial layer, wherein setting the passivation layer prior to setting a first conductive material, setting the first conductive material over a first portion of the substrate includes patterning the first conductive material such that the first conductive material is aligned over the sacrificial layer, and wherein the passivation layer forms at least a portion of a first electrode in the region overlapping with the first conductive material.

[0192] Example 5 is the method of Example 4, and also includes: removing the sacrificial layer adjacent to the passivation layer.

[0193] Example 6 is a method of Example 1, wherein removing a portion of the substrate includes reducing the thickness of the substrate.

[0194] Example 7 is a method of manufacturing a fluid device, the method comprising: forming a bulk acoustic wave resonator structure, wherein forming the bulk acoustic wave resonator structure includes: disposing a first conductive material over a portion of a first surface of a substrate to form at least a portion of a first electrode; disposing a piezoelectric material over the first conductive material; disposing a second conductive material over the piezoelectric material to form at least a portion of a second electrode, wherein the second conductive material extends substantially parallel to the first surface of the substrate and extends at least partially over the first conductive material, wherein the overlapping region of the first conductive material, the piezoelectric material, and the second conductive material forms a bulk acoustic wave resonator; disposing a reflector structure over a first side of the bulk acoustic wave resonator; disposing a third conductive material over a portion of the second conductive material extending beyond the bulk acoustic wave resonator, wherein the third conductive material forms an interconnect extending over the reflector structure in a direction substantially perpendicular to the first surface of the substrate; and removing a portion of the substrate to expose the first electrode on a second side of the bulk acoustic wave resonator; and mounting the bulk acoustic wave resonator structure to a base, wherein mounting the bulk acoustic wave resonator includes coupling the interconnect to the base.

[0195] Example 8 is a method of Example 7, further comprising: placing an adhesive layer between the bulk acoustic resonator structure and the base.

[0196] Example 9 is the method of Example 7, and further includes: setting a functionalized material on the second electrode.

[0197] Example 10 is the method of Example 7, and further includes: attaching a cavity wall to the base, wherein the cavity wall surrounds the periphery of the bulk acoustic resonator structure.

[0198] Example 11 is a method of Example 10, further comprising placing a cover on the cavity wall, wherein the cover includes a fluid inlet and a fluid outlet.

[0199] Example 12 is the method of Example 7, further comprising: defining a fluid path within a substrate adjacent to the second electrode.

[0200] Example 13 is the method of Example 7, wherein removing a portion of the substrate includes reducing the thickness of the substrate.

[0201] Example 14 is the method of Example 7, and further includes: after mounting the bulk acoustic resonator to the base, placing a functionalized material on the second electrode.

[0202] Example 15 is a fluid device comprising: a bulk acoustic wave resonator structure, the bulk acoustic wave resonator structure including: a bulk acoustic wave resonator disposed below a substrate, wherein the bulk acoustic wave resonator includes a first electrode disposed above a portion of a first surface of the substrate, a piezoelectric material disposed above the first electrode, and a second electrode disposed above the piezoelectric material, wherein an overlapping region of the first electrode, the piezoelectric material, and the second electrode forms the bulk acoustic wave resonator; a reflector structure disposed above a first side of the bulk acoustic wave resonator; an interconnect disposed above the second electrode extending beyond a portion of the bulk acoustic wave resonator, wherein the interconnect extends at the height of the reflector structure in a direction substantially perpendicular to the first surface of the substrate, and wherein the substrate includes an opening extending from a second surface of the substrate to the first electrode; a functionalized material disposed above the first electrode at the opening; a base electrically coupled to the interconnect; a cavity wall extending from the base and surrounding the bulk acoustic wave resonator structure; and a fluid cavity at least partially defined by the substrate and the cavity wall.

[0203] Example 16 is a method of Example 15, wherein the bulk acoustic resonator structure includes a cavity resonator.

[0204] Example 17 is a method of Example 15, wherein the bulk acoustic resonator includes a thin-film bulk acoustic resonator.

[0205] Example 18 is a method of Example 15, wherein the substrate includes fluid channels.

[0206] Example 19 is a method of Example 15, wherein the bulk acoustic resonator structure includes a plurality of bulk acoustic resonators, each of the plurality of bulk acoustic resonators including an associated reflector structure and interconnects for independently electrically coupling each of the plurality of bulk acoustic resonators to a base.

[0207] Example 20 is the method of Example 19, wherein a plurality of bulk acoustic resonators are arranged along the substrate in a row and column pattern.

[0208] Although this disclosure has been described with reference to preferred embodiments, those skilled in the art will recognize that changes in form and detail may be made without departing from the spirit and scope of this disclosure.

Claims

1. A method for manufacturing a bulk acoustic resonator structure for a fluid device, comprising: A first conductive material is disposed above a portion of a first surface of a substrate to form at least a portion of a first electrode, the substrate having a second surface opposite to the first surface; A piezoelectric material is disposed above the first electrode; A second conductive material is disposed above the piezoelectric material to form at least a portion of the second electrode, wherein the second conductive material extends substantially parallel to the first surface of the substrate, and the second conductive material extends at least partially above the first conductive material, wherein the overlapping region of the first conductive material, the piezoelectric material, and the second conductive material forms a bulk acoustic resonator, the bulk acoustic resonator having a first side and an opposing second side; An acoustic energy management structure is provided above the first side of the bulk acoustic resonator; A third conductive material is disposed above a portion of the second conductive material extending beyond the bulk acoustic resonator, wherein the third conductive material forms an interconnect that extends above the acoustic energy management structure in a direction substantially perpendicular to the first surface of the substrate; A portion of the second surface of the substrate is removed to expose the chemical mechanical connection at the first electrode on the second side of the bulk acoustic resonator; as well as The bulk acoustic wave resonator structure is mounted to the base, wherein mounting the bulk acoustic wave resonator includes coupling the interconnect to the base such that the bulk acoustic wave resonator is located between the substrate and the base.

2. The method of claim 1, wherein removing a portion of the substrate comprises reducing the thickness of the substrate.

3. The method of claim 2, wherein the thickness of the substrate is reduced to 200 micrometers to 400 micrometers.

4. A method for manufacturing a fluid device, the method comprising: Forming a bulk acoustic resonator structure, wherein forming the bulk acoustic resonator structure includes: A first conductive material is disposed over a portion of a first surface of a substrate to form at least a portion of a first electrode. A piezoelectric material is disposed above the first conductive material; A second conductive material is disposed above the piezoelectric material to form at least a portion of the second electrode, wherein the second conductive material extends substantially parallel to the first surface of the substrate, and at least partially extends above the first conductive material, wherein the overlapping region of the first conductive material, the piezoelectric material, and the second conductive material forms a bulk acoustic resonator. A reflector structure including an acoustic reflector is formed above the first side of the bulk acoustic resonator. A third conductive material is disposed above a portion of the second conductive material extending beyond the bulk acoustic resonator, wherein the third conductive material forms an interconnect that extends above the reflector structure in a direction substantially perpendicular to the first surface of the substrate. Removing a portion of the substrate to expose the first electrode on the second side of the bulk acoustic resonator; and The bulk acoustic wave resonator structure is mounted to the base, wherein mounting the bulk acoustic wave resonator includes coupling the interconnect to the base such that the bulk acoustic wave resonator is located between the substrate and the base.

5. The method of claim 4, wherein the step of forming the acoustic reflector includes setting alternating layers of material, wherein the alternating layers of material are selected from: silicon oxycarbonate [SiOC], silicon nitride [Si3N4], silicon dioxide [SiO2], aluminum nitride [AlN], tungsten [W], and molybdenum [Mo].

6. A method for manufacturing a fluid device, the method comprising: Forming a bulk acoustic resonator structure, wherein forming the bulk acoustic resonator structure includes: A first conductive material is disposed over a portion of a first surface of a substrate to form at least a portion of a first electrode. A piezoelectric material is disposed above the first conductive material; A second conductive material is disposed above the piezoelectric material to form at least a portion of the second electrode, wherein the second conductive material extends substantially parallel to the first surface of the substrate, and at least partially extends above the first conductive material, wherein the overlapping region of the first conductive material, the piezoelectric material, and the second conductive material forms a bulk acoustic resonator. A reflector structure including an air cavity is formed above the first side of the bulk acoustic resonator. A third conductive material is disposed above a portion of the second conductive material extending beyond the bulk acoustic resonator, wherein the third conductive material forms an interconnect that extends above the reflector structure in a direction substantially perpendicular to the first surface of the substrate. Removing a portion of the substrate to expose the first electrode on the second side of the bulk acoustic resonator; and The bulk acoustic wave resonator structure is mounted to the base, wherein mounting the bulk acoustic wave resonator includes coupling the interconnect to the base such that the bulk acoustic wave resonator is located between the substrate and the base.

7. The method of claim 6, wherein the step of forming the air cavity includes forming at least one wall and a top of a photoimageable material.

8. A fluid device, comprising: A bulk acoustic resonator structure, the bulk acoustic resonator structure comprising: A bulk acoustic wave resonator disposed under a substrate, wherein the bulk acoustic wave resonator includes a first electrode disposed above a portion of a first surface of the substrate, a piezoelectric material disposed above the first electrode, and a second electrode disposed above the piezoelectric material, wherein the overlapping region of the first electrode, the piezoelectric material, and the second electrode forms the bulk acoustic wave resonator. A sound energy management structure disposed above the first side of the bulk acoustic resonator; An interconnect disposed above the second electrode extending beyond a portion of the bulk acoustic resonator, wherein the interconnect extends above the height of the acoustic energy management structure in a direction substantially perpendicular to the first surface of the substrate, and The substrate includes an opening extending from a second surface of the substrate to the first electrode; Functionalized material disposed above the opening of the first electrode; Electrically coupled to the base of the interconnect, wherein the bulk acoustic resonator is located between the substrate and the base; The cavity wall extending from the base and surrounding the bulk acoustic resonator structure; and A fluid cavity defined at least in part by the substrate and the cavity wall.

9. The fluid device of claim 8, wherein the acoustic energy management structure comprises at least one wall and a top containing a photoimageable material, and wherein the top has an area of ​​100 square micrometers to 500,000 square micrometers.

10. The fluid device of claim 8, wherein the acoustic energy management structure comprises an acoustic reflector comprising alternating layers selected from the materials: silicon oxycarbonate [SiOC], silicon nitride [Si3N4], silicon dioxide [SiO2], aluminum nitride [AlN], tungsten [W], and molybdenum [Mo].

Images