Acoustic droplet ejection method, apparatus with fluid replenishment structure and method of manufacturing thereof

Abstract

Embodiments of the present application provide an acoustic droplet ejection method and device with a liquid supplementing structure and a manufacturing method thereof. The device comprises a substrate, a bulk acoustic wave driver and a liquid chamber. The liquid chamber has a chamber capable of containing a liquid layer and a liquid supplementing channel capable of supplementing the liquid layer. Thus, the liquid supplementing channel can supplement the liquid in time even when the ejection is at a high throughput, effectively ensuring the stability of the liquid surface height during ejection and realizing long-time ejection.

Description

Technical Field

[0001] This application relates to the field of electronic technology, and in particular to an acoustic droplet ejection method, apparatus and manufacturing method of having a liquid replenishment structure. Background Technology

[0002] Traditional droplet generation technologies mainly include microfluidics, optical focusing jetting, and extrusion. Microfluidics employs a passive structure, resulting in uncontrollable droplet diameters. Optical focusing jetting, due to its high energy, causes significant damage to droplet formation, especially in biological applications. Extrusion is currently the primary technology used in inkjet printing, encompassing thermal foaming and piezoelectric methods.

[0003] Thermal foaming primarily utilizes a heating element to instantly generate high temperatures, stimulating and producing bubbles. These bubbles expand, compressing the liquid to form droplets, resulting in high energy density and high spraying efficiency. Furthermore, the heating element is relatively easy to control and miniaturize. However, the high temperatures generated during thermal foaming lead to rapid liquid evaporation, and the droplet diameter cannot be controlled. Piezoelectric methods utilize piezoelectric materials such as piezoelectric ceramics to drive deformation, thereby compressing liquid and ejecting it from a cavity to form droplets. These methods also face the problem of uncontrollable droplet diameter.

[0004] On the other hand, sound wave-based droplet jetting technology is widely used due to its good biocompatibility and nozzle-free structure. Currently, droplet jetting devices based on surface acoustic waves have been proposed. Because surface acoustic waves propagate along the surface of an object, this structure can complete the jetting without contact with the liquid.

[0005] However, the inventors discovered that this droplet ejection device, which replenishes the liquid to the ejection area via a capillary tube, cannot replenish the liquid in a timely manner during high-flux ejection. Furthermore, the energy is not concentrated during droplet ejection, resulting in high power requirements; the droplet ejection direction is inconsistent; the droplet diameter cannot be precisely controlled; the ejected droplet flux is low; and the device size is relatively large, among other issues. Summary of the Invention

[0006] To address at least one of the aforementioned problems or other similar issues, embodiments of this application provide an acoustic droplet injection method, apparatus, and manufacturing method thereof with a liquid replenishment structure.

[0007] According to a first aspect of the embodiments of this application, an acoustic droplet ejection device with a liquid replenishment structure is provided, comprising:

[0008] Substrate;

[0009] A bulk acoustic wave actuator, located on the upper side of the substrate and having a vibration region;

[0010] A liquid cavity, at least partially located above the bulk acoustic wave driver, the liquid cavity having a chamber capable of containing a liquid layer and a replenishment channel capable of replenishing the liquid layer;

[0011] The bulk acoustic wave driver includes:

[0012] An acoustic reflective layer is located on the upper side of the substrate;

[0013] The first electrode is located on the upper side of the acoustic reflective layer;

[0014] A piezoelectric layer, at least partially located above the first electrode;

[0015] A second electrode is located above the piezoelectric layer; wherein the first electrode, the piezoelectric layer, and the second electrode at least partially overlap in a direction perpendicular to the substrate to form the vibration region.

[0016] Therefore, by using a replenishment channel, liquid can be replenished in a timely manner even during high-throughput spraying, effectively ensuring the stability of the liquid level height during spraying and enabling long-term spraying. By having the first electrode, piezoelectric layer, and second electrode at least partially overlap in a direction perpendicular to the substrate to form a vibration region, bulk acoustic waves propagate along the vertical direction and are reflected by an acoustic reflection layer. When in contact with the liquid layer, the high-frequency acoustic waves couple into the liquid layer, generating volume forces, thus concentrating the energy during liquid spraying and requiring lower spraying power. This structure allows for a smaller bulk acoustic wave actuator size and a higher throughput of sprayed droplets.

[0017] According to a second aspect of the embodiments of this application, the liquid cavity has a nozzle at a position corresponding to the vibration region.

[0018] As a result, droplets are ejected from the nozzle, and the diameter of the ejected droplets is more uniform; and because the driver has low power consumption and low heat dissipation, there will be no nozzle clogging problem.

[0019] According to a third aspect of the embodiments of this application, the nozzle is circular, elliptical, or polygonal in shape.

[0020] According to a fourth aspect of the embodiments of this application, when viewed from a direction perpendicular to the substrate, the nozzle and the vibration region at least partially overlap.

[0021] According to a fifth aspect of the embodiments of this application, the height of the chamber in the direction perpendicular to the substrate is from 1 micrometer to 300 micrometers.

[0022] According to a sixth aspect of the embodiments of this application, the apparatus further includes:

[0023] A passivation layer is located between the second electrode and the liquid layer.

[0024] This isolates the bulk acoustic wave actuator from the liquid, protecting it and thus improving the quality and lifespan of the device.

[0025] According to a seventh aspect of the embodiments of this application, the acoustic reflective layer includes a baffle layer structure and / or an air cavity structure.

[0026] According to an eighth aspect of the embodiments of this application, the apparatus further includes

[0027] An integrated circuit is located on the substrate; and the bulk acoustic wave driver is located on top of the integrated circuit.

[0028] According to a ninth aspect of the present application, the first electrode is connected to a first conductive portion of the integrated circuit via a first interface portion; the second electrode is connected to a second conductive portion of the integrated circuit via a second interface portion.

[0029] Therefore, the droplet ejection device can be controlled by integrated circuits on the substrate, which is compatible with CMOS technology, and the driver control method after array is flexible and small in size.

[0030] According to a tenth aspect of the present application, one or more of the bulk acoustic wave drivers are included on the substrate.

[0031] According to an eleventh aspect of the embodiments of this application, a plurality of bulk acoustic wave actuators are respectively located on the upper side of the substrate, and a predetermined distance is spaced between two adjacent bulk acoustic wave actuators.

[0032] Therefore, the droplet jet structure of the bulk acoustic wave actuator, which can be arranged in an array, is beneficial for product miniaturization.

[0033] According to a twelfth aspect of the present application, when the sound wave is transmitted to the liquid layer, it pushes the liquid and causes attenuation, the attenuation causing a volume force and causing the liquid to overcome surface tension to form the droplet.

[0034] According to a thirteenth aspect of the present application, the droplet is ejected through a nozzle in the liquid cavity at a position corresponding to the vibration region.

[0035] According to a fourteenth aspect of the present application, a pulse signal is applied to the first and second electrodes of the bulk acoustic wave driver in the acoustic droplet ejection device via an integrated circuit in the device.

[0036] According to a fifteenth aspect of the present application, an acoustic droplet ejection method having a replenishment structure is provided, the method using the above-described acoustic droplet ejection device, the method comprising:

[0037] A pulse signal is applied to the first and second electrodes of the bulk acoustic wave driver in the acoustic droplet ejection device;

[0038] Droplets are ejected from the liquid layer of the acoustic droplet ejection device; and

[0039] The liquid layer is replenished through the replenishment channel within the liquid chamber;

[0040] When the pulse signal is applied to the first electrode and the second electrode, the piezoelectric layer of the acoustic droplet ejection device vibrates in the vibration region and forms a sound wave. At least part of the sound wave is reflected by the acoustic reflection layer of the acoustic droplet ejection device and transmitted to the liquid layer. The sound wave is coupled into the liquid layer to generate a volume force, causing the liquid layer to eject the droplet.

[0041] Therefore, by using a replenishment channel, liquid can be replenished in a timely manner even during high-throughput spraying, effectively ensuring the stability of the liquid level height during spraying and enabling long-term spraying. By having the first electrode, piezoelectric layer, and second electrode at least partially overlap in a direction perpendicular to the substrate to form a vibration region, bulk acoustic waves propagate along the vertical direction and are reflected by an acoustic reflection layer. When in contact with the liquid layer, the high-frequency acoustic waves couple into the liquid layer, generating volume forces, thus concentrating the energy during liquid spraying and requiring lower spraying power. This structure allows for a smaller bulk acoustic wave actuator size and a higher throughput of sprayed droplets.

[0042] According to a sixteenth aspect of the present application, when the sound wave is transmitted to the liquid layer, it pushes the liquid and causes attenuation, the attenuation causing a volume force and causing the liquid to overcome surface tension to form the droplet.

[0043] Therefore, droplet ejection is driven by the volume force generated by attenuation in a liquid environment.

[0044] According to a seventeenth aspect of the present application, the droplet is ejected through a nozzle in the liquid cavity at a position corresponding to the vibration region.

[0045] As a result, the droplet diameter can be further precisely controlled, resulting in good uniformity.

[0046] According to the eighteenth aspect of the present application, a pulse signal is applied to the first electrode and the second electrode of the bulk acoustic wave driver in the acoustic droplet ejection device via an integrated circuit in the acoustic droplet ejection device.

[0047] Therefore, the droplet ejection device can be controlled by integrated circuits on the substrate, which is compatible with CMOS technology, and the driver control method after array is flexible and small in size.

[0048] According to a nineteenth aspect of the embodiments of this application, a method for manufacturing an acoustic droplet ejection device having a liquid replenishment structure is provided, comprising:

[0049] A bulk acoustic wave actuator is formed, the bulk acoustic wave actuator being located on the upper side of the substrate and having a vibration region; and

[0050] A liquid cavity is formed, at least partially located above the bulk acoustic wave driver, the liquid cavity having a chamber capable of accommodating a liquid layer and a replenishment channel capable of replenishing the liquid layer;

[0051] The forming bulk acoustic wave driver includes:

[0052] An acoustic reflection layer is formed on the upper side of the substrate;

[0053] A first electrode is formed on the upper side of the acoustic reflective layer;

[0054] A piezoelectric layer is formed on the upper side of the first electrode; and

[0055] A second electrode is formed on the upper side of the piezoelectric layer; wherein the first electrode, the piezoelectric layer and the second electrode at least partially overlap in a direction perpendicular to the substrate to form the vibration region.

[0056] Therefore, by using a replenishment channel, liquid can be replenished in a timely manner even during high-throughput spraying, effectively ensuring the stability of the liquid level height during spraying and enabling long-term spraying. By having the first electrode, piezoelectric layer, and second electrode at least partially overlap in a direction perpendicular to the substrate to form a vibration region, bulk acoustic waves propagate along the vertical direction and are reflected by an acoustic reflection layer. When in contact with the liquid layer, the high-frequency acoustic waves couple into the liquid layer, generating volume forces, thus concentrating the energy during liquid spraying and requiring lower spraying power. This structure allows for a smaller size and higher droplet throughput in the bulk acoustic wave actuator. The bulk acoustic wave actuator can be fabricated using microelectromechanical systems (MEMS) technology and can be easily integrated with complementary metal-oxide-semiconductor (CMOS) technology.

[0057] According to a twentieth aspect of the embodiments of this application, the method further includes:

[0058] A passivation layer is formed between the second electrode and the liquid layer.

[0059] According to a twenty-first aspect of the embodiments of this application, the formation of the liquid cavity includes:

[0060] A sacrificial layer is formed on the bulk acoustic wave driver;

[0061] The liquid cavity is formed on the sacrificial layer; and

[0062] The sacrificial layer is released to form the replenishment channel and the chamber that contains the liquid layer.

[0063] According to a twenty-second aspect of the embodiments of this application, the method further includes:

[0064] An integrated circuit is formed, wherein the integrated circuit is located on the upper side of the substrate.

[0065] According to a twenty-third aspect of the present application, when a first electrode is formed on the upper side of the acoustic reflection layer, the first electrode is connected to a first conductive portion of the integrated circuit through a first interface portion;

[0066] When a second electrode is formed on the upper side of the piezoelectric layer, the second electrode is connected to the second conductive part of the integrated circuit through a second interface portion.

[0067] According to a twenty-fourth aspect of the present application, one or more of the bulk acoustic wave drivers are formed on the substrate.

[0068] According to a twenty-fifth aspect of the present application, a plurality of bulk acoustic wave actuators are respectively located on the upper side of the substrate, and a predetermined distance is spaced between two adjacent bulk acoustic wave actuators.

[0069] According to a twenty-sixth aspect of the present application, an electrical product is provided, the electrical product having the acoustic droplet ejection device as described above.

[0070] One of the beneficial effects of this application's embodiments is that, through the replenishment channel, liquid can be replenished in a timely manner even during high-throughput spraying, effectively ensuring the stability of the liquid level height during spraying and enabling long-term spraying. By having the first electrode, piezoelectric layer, and second electrode at least partially overlap in a direction perpendicular to the substrate to form a vibration region, bulk acoustic waves propagate along the vertical direction and are reflected by the acoustic reflection layer. When in contact with the liquid layer, the high-frequency acoustic waves couple into the liquid layer to generate volume forces, thus concentrating the energy during liquid spraying and requiring lower spraying power. This structure allows for a smaller bulk acoustic wave actuator size and a higher throughput of sprayed droplets.

[0071] Embodiments of this application are disclosed in detail with reference to the following description and accompanying drawings. It should be understood that the scope of embodiments of this application is not limited thereto. Within the spirit and scope of the appended claims, embodiments of this application include many changes, modifications, and equivalents.

[0072] Features described and / or illustrated for one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments.

[0073] It should be emphasized that the term "including / contains / has" as used herein refers to the presence of a feature, whole or component, but does not exclude the presence or addition of one or more other features, wholes or components. Attached Figure Description

[0074] The above and other objects, features and advantages of the embodiments of this application will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0075] Figure 1 This is a schematic diagram of an acoustic droplet ejection device according to an embodiment of this application;

[0076] Figure 2 This is a cross-sectional view of the acoustic droplet ejection device according to an embodiment of this application;

[0077] Figure 3 This is another cross-sectional view of the acoustic droplet ejection device according to an embodiment of this application;

[0078] Figure 4 These are some example diagrams of nozzles according to embodiments of this application;

[0079] Figure 5 This is an example diagram of a bulk acoustic wave driver according to an embodiment of this application;

[0080] Figure 6 This is another example diagram of a bulk acoustic wave driver according to an embodiment of this application;

[0081] Figure 7 This is another cross-sectional view of the acoustic droplet ejection device according to an embodiment of this application;

[0082] Figure 8 This is another cross-sectional view of the acoustic droplet ejection device according to an embodiment of this application;

[0083] Figure 9 This is a schematic diagram of an acoustic droplet ejection method with a replenishing structure according to an embodiment of this application;

[0084] Figure 10 This is a schematic diagram of a method for manufacturing an acoustic droplet ejection device with a replenishment structure according to an embodiment of this application;

[0085] Figure 11 This is an example diagram of the fabrication of an acoustic reflective layer according to an embodiment of this application;

[0086] Figure 12 This is an example diagram of the manufacturing of the first electrode according to an embodiment of this application;

[0087] Figure 13 This is an example diagram of the fabrication of a piezoelectric layer according to an embodiment of this application;

[0088] Figure 14This is an example diagram of the manufacturing of the second electrode according to an embodiment of this application;

[0089] Figure 15 This is an example diagram of the fabrication of the passivation layer according to an embodiment of this application;

[0090] Figure 16 This is an example diagram of a patterned device according to an embodiment of this application;

[0091] Figure 17 This is an example diagram of an etching fluid replenishment channel according to an embodiment of this application;

[0092] Figure 18 This is an example diagram illustrating the preparation of the sacrificial layer according to an embodiment of this application;

[0093] Figure 19 This is an example diagram of photolithography performed on the sacrificial layer according to an embodiment of this application;

[0094] Figure 20 This is an example diagram of the preparation of a liquid cavity according to an embodiment of this application;

[0095] Figure 21 This is an example diagram of the preparation nozzle according to an embodiment of this application;

[0096] Figure 22 This is an example diagram of the preparation of the fluid replenishment channel and chamber according to an embodiment of this application;

[0097] Figure 23 This is an example diagram of the fabrication of an acoustic reflective layer according to an embodiment of this application;

[0098] Figure 24 This is an example diagram of the manufacturing of the first electrode according to an embodiment of this application;

[0099] Figure 25 This is another example diagram of the manufacturing of the first electrode according to an embodiment of this application;

[0100] Figure 26 This is an example diagram of the fabrication of a piezoelectric layer according to an embodiment of this application;

[0101] Figure 27 This is an example diagram of the manufacturing of a dielectric layer according to an embodiment of this application;

[0102] Figure 28 This is an example diagram of the manufacturing of the second electrode according to an embodiment of this application;

[0103] Figure 29 This is another example diagram of the manufacturing of the second electrode according to an embodiment of this application;

[0104] Figure 30 This is an example diagram of the fabrication of the passivation layer according to an embodiment of this application;

[0105] Figure 31This is an example diagram of an etching fluid replenishment channel according to an embodiment of this application;

[0106] Figure 32 This is an example diagram illustrating the preparation of the sacrificial layer according to an embodiment of this application;

[0107] Figure 33 This is an example diagram of the preparation of a liquid cavity according to an embodiment of this application;

[0108] Figure 34 This is an example diagram of the preparation nozzle according to an embodiment of this application;

[0109] Figure 35 This is an example diagram of the preparation and replenishment channel according to an embodiment of this application. Detailed Implementation

[0110] Referring to the accompanying drawings, the foregoing and other features of this application will become apparent from the following description. Specific embodiments of this application are specifically disclosed in the description and drawings, illustrating partial implementations in which the principles of this application may be employed. It should be understood that this application is not limited to the described embodiments; rather, it includes all modifications, variations, and equivalents falling within the scope of the appended claims.

[0111] In embodiments of this application, the term "and / or" includes any one and all combinations of one or more of the terms listed in association. The terms "comprising," "including," "having," etc., refer to the presence of the stated features, elements, components, or assemblies, but do not exclude the presence or addition of one or more other features, elements, components, or assemblies.

[0112] In the embodiments of this application, the singular forms "a," "the," etc., may include the plural forms and should be broadly interpreted as "a kind" or "a class" rather than limited to the meaning of "an." Furthermore, the term "the" should be understood to include both the singular and plural forms unless the context explicitly indicates otherwise. Additionally, the term "according to" should be understood as "at least partially based on…," and the term "based on" should be understood as "at least partially based on…," unless the context explicitly indicates otherwise.

[0113] Furthermore, in the following description of this application, for ease of explanation, one side of the substrate (also referred to as the base plate or substrate) is referred to as the lower side or the bottom side, and one side of the liquid layer or the side from which the droplets are ejected is referred to as the upper side or the top side. However, it should be noted that these are only for the convenience of explanation and do not limit the orientation of the acoustic droplet ejection device of the embodiments of this application during manufacturing and use.

[0114] The embodiments of this application will now be described with reference to the accompanying drawings.

[0115] This application provides an acoustic droplet ejection device. Figure 1 This is a schematic diagram of an acoustic droplet ejection device according to an embodiment of this application. Figure 2 This is a cross-sectional view of the acoustic droplet ejection device. Figure 3 This is another cross-sectional view of the acoustic droplet ejection device. (See diagram below.) Figures 1 to 3 As shown, the acoustic droplet ejection device 10 includes:

[0116] Substrate 11;

[0117] A bulk acoustic wave actuator 12 is located on the upper side of the substrate 11 and has a vibration region 13;

[0118] A liquid cavity 16, at least partially located above the bulk acoustic wave driver 12, has a chamber 141 capable of accommodating a liquid layer 14 and a replenishment channel 161 capable of replenishing the liquid layer 14; wherein the liquid layer 14 is at least partially located above the vibration region 13.

[0119] like Figure 1 and Figure 2 As shown, the bulk acoustic wave driver 12 includes:

[0120] An acoustic reflective layer 121 is located on the upper side of the substrate 11;

[0121] The first electrode 122 is located on the upper side of the acoustic reflective layer 121;

[0122] A piezoelectric layer 123 is located at least partially above the first electrode 122;

[0123] The second electrode 124 is located above the piezoelectric layer 123; wherein the first electrode 122, the piezoelectric layer 123 and the second electrode 124 at least partially overlap in a direction perpendicular to the substrate 11 to form the vibration region 13.

[0124] like Figure 1 and Figure 2 As shown, the acoustic droplet ejection device 10 further includes a liquid layer 14, which is at least partially located above the vibration region 13 of the bulk acoustic wave actuator 12. This liquid layer 14 can be formed during manufacturing or product shipment, or it can be formed after shipment when it is needed for use; this application is not limited thereto. Furthermore, as... Figure 2 As shown, the liquid layer 14 can be contained in the liquid cavity 16, but this application is not limited to this. For example, the liquid layer 14 can also be formed by liquid tension, as long as the liquid layer 14 covers the vibration region 13.

[0125] Therefore, by using a replenishment channel, liquid can be replenished in a timely manner even during high-throughput spraying, effectively ensuring the stability of the liquid level height during spraying and enabling long-term spraying. By having the first electrode, piezoelectric layer, and second electrode at least partially overlap in a direction perpendicular to the substrate to form a vibration region, bulk acoustic waves propagate along the vertical direction and are reflected by an acoustic reflection layer. When in contact with the liquid layer, the high-frequency acoustic waves couple into the liquid layer, generating volume forces, thus concentrating the energy during liquid spraying and requiring lower spraying power. This structure allows for a smaller bulk acoustic wave actuator size and a higher throughput of sprayed droplets.

[0126] In some embodiments, the height of the chamber 141 in the direction perpendicular to the substrate 11 is 1 micrometer to 300 micrometers, thereby forming a liquid layer 14 of a corresponding thickness; however, this application is not limited thereto.

[0127] In some embodiments, such as Figure 2 and Figure 3 As shown, the liquid chamber 16 has a nozzle 162 at a position corresponding to the vibration region 13. Figure 3 As shown, the liquid layer 14 can be formed in the chamber 141 within the liquid cavity 16. Through the vibration of the vibration region 13, the droplets 17 are ejected from the nozzle 162. The liquid layer 14 can be replenished through the replenishment channel 161.

[0128] As a result, droplets are ejected from the nozzle, and the diameter of the ejected droplets is more uniform; and because the driver has low power consumption and low heat dissipation, there will be no nozzle clogging problem.

[0129] In some embodiments, the nozzle is circular, elliptical, or polygonal in shape, but this application is not limited to these and may also have other shapes.

[0130] In some embodiments, from the direction perpendicular to the substrate 11 (i.e. Figure 2 When viewed from above and below, the nozzle 162 and the vibration area 13 should at least partially overlap. For example, the area of ​​the nozzle 162 can be larger than the area of ​​the vibration area 13, or the area of ​​the nozzle 162 can be smaller than the area of ​​the vibration area 13, as long as its position overlaps with the vibration area to a certain extent in the vertical direction.

[0131] Figure 4 These are some example diagrams of the nozzles according to embodiments of this application, showing some aspects of the acoustic droplet ejection device from a top view. For example... Figure 4 As shown on the left, the diameter of the corresponding nozzle 162 can be approximately equal to that of the vibration region 13, and the positions of the nozzle 162 and the actuator can be concentrically distributed; as shown on the left. Figure 4As shown on the right, the diameter of the corresponding nozzle 162 may not be equal to that of the vibration region 13. Furthermore, the positions of the nozzle 162 and the driver may not be concentrically distributed. The embodiments of this application are not limited thereto.

[0132] In some embodiments, the materials of the first electrode 122 and the second electrode 124 can be various metals suitable for semiconductor manufacturing processes, such as aluminum, molybdenum, tungsten, and copper. The material of the piezoelectric layer 123 can include single-crystal and polycrystalline aluminum nitride, single-crystal and polycrystalline doped aluminum nitride, zinc oxide, lithium niobate, lithium tantalate, lead zirconate titanate, etc.; the thickness of the piezoelectric layer 123 mainly determines the vibration frequency of the bulk acoustic wave actuator 12, i.e., the operating frequency and the frequency of the corresponding applied high-frequency signal.

[0133] A liquid layer 14 is placed within a liquid cavity 16, which may be made of organic or inorganic materials such as metal, glass, or PDMS. The liquid layer 14 may contain water, ink, or other liquids. The liquid layer 14 may be formed only during use, for example, by injecting liquid into the chamber 141 within the liquid cavity 16; however, this application is not limited to this.

[0134] In some embodiments, the acoustic reflective layer comprises a braided layer structure and / or an air cavity structure. For example, the acoustic reflective layer comprises a braided layer structure; another example is that the acoustic reflective layer comprises an air cavity structure; yet another example is that the acoustic reflective layer comprises both a braided layer structure and an air cavity structure; this application is not limited to these, and other structures are also possible.

[0135] Figure 5 This is an example diagram of a bulk acoustic wave driver according to an embodiment of this application, showing an example where the acoustic reflector layer 121 is a Bragg reflector layer. For example, it can be made of silicon dioxide with a material of 0.65 micrometers (such as... Figure 5 (as shown in 501) and 0.64 micrometers of molybdenum (as shown in 501) Figure 5 The Bragg reflector layer is formed by sequentially depositing (as shown in 502). That is, a five-layer structure of silicon dioxide---molybdenum---silicon dioxide---molybdenum---silicon dioxide is formed, but the embodiments of this application are not limited to this.

[0136] Figure 6 This is another example diagram of a bulk acoustic wave driver according to an embodiment of this application, showing an example where the acoustic reflection layer 121 is a chamber structure. For example, a chamber 601 may be formed in the substrate 11 as the acoustic reflection layer 121, but the embodiments of this application are not limited thereto.

[0137] In some embodiments, such as Figure 6 As shown, the acoustic droplet ejection device 10 may further include

[0138] A passivation layer 15 is located above the second electrode 124. For example, the passivation layer 15 is formed between the second electrode 124 and the liquid layer 14.

[0139] Therefore, the passivation layer can isolate the bulk acoustic wave actuator from the liquid, thus protecting the bulk acoustic wave actuator and improving the quality and service life of the device.

[0140] In some embodiments, the thickness of the passivation layer 15 is less than 200 nanometers.

[0141] Therefore, the passivation layer is relatively thin, which can reduce the impact on the performance of the bulk acoustic wave driver.

[0142] Furthermore, the passivation layer 15 can be further optimized to enhance its corrosion resistance, and its hydrophilic / hydrophobic properties facilitate liquid jetting. For example, the material of the passivation layer 15 can be an insulating material resistant to organic / inorganic corrosion, such as aluminum nitride, silicon carbide, silicon nitride, or silicon dioxide. The area of ​​the passivation layer 15 can be limited to covering the driver or can cover the entire wafer surface, providing a substrate for the subsequent fabrication of the flow channel and nozzle system.

[0143] The above Figure 6 The example given is a passivation layer 15, but this application is not limited to this. Figures 1 to 5 The device may also have a passivation layer 15.

[0144] In some embodiments, the area of ​​the vibration region of the bulk acoustic wave actuator is from 10 square micrometers to 20,000 square micrometers.

[0145] In some embodiments, the thickness of the liquid layer is from 1 micrometer to 1 millimeter. For example, it can be from 10 micrometers to 300 micrometers, or from 10 micrometers to 100 micrometers, and so on.

[0146] In some embodiments, the vibration frequency of the bulk acoustic wave driver is from 0.1 GHz to 5 GHz.

[0147] Therefore, due to the small size of the bulk acoustic wave actuator, more structures can be arrayed per unit area; and the pulse signal applied by the bulk acoustic wave actuator has a short period, which can eject thousands or even tens of thousands of droplets per second, resulting in a high flux of droplet ejection.

[0148] For example, the first electrode 122 and the second electrode 124 are made of molybdenum; the piezoelectric layer 123 is made of aluminum nitride and has a thickness of 1.1 micrometers, which mainly determines the vibration frequency of the droplet ejection device, i.e., the operating frequency is 2.46 GHz; the liquid layer 14 is placed inside the liquid cavity 16, which is made of glass and has a thickness of 150 μm; a passivation layer 15 is located between the second electrode 124 and the liquid layer 14 to isolate the second electrode 124 from the liquid, and the passivation layer 15 has a thickness of, for example, 100 nanometers and is made of aluminum nitride. The above parameters are merely some examples of embodiments of this application, and this application is not limited thereto.

[0149] Figure 7 This is another cross-sectional view of the acoustic droplet ejection device according to an embodiment of this application, showing a case with a simplified structure. For example... Figure 2 and Figure 3 As shown, flow channel structures for increasing fluid resistance can be provided upstream and downstream of the bulk acoustic wave actuator 12, but this application is not limited to this. Figure 7 As shown, since the bulk acoustic wave actuator uses sound waves to eject droplets, a simple liquid replenishment structure can be used without the need for a complex liquid replenishment circulation system.

[0150] The above provides an illustrative description of the apparatus according to the embodiments of this application. The spraying apparatus of this application can also be controlled by an integrated circuit.

[0151] In some embodiments, the device further includes: an integrated circuit located on the substrate; and a bulk acoustic wave driver located above the integrated circuit. For example, the first electrode is connected to a first conductive portion of the integrated circuit via a first interface portion; and the second electrode is connected to a second conductive portion of the integrated circuit via a second interface portion.

[0152] Figure 8 This is another cross-sectional view of the acoustic droplet ejection device according to an embodiment of this application, showing the case with integrated circuit control. For example... Figure 8 As shown, the acoustic droplet ejection device 80 includes:

[0153] Substrate 11;

[0154] An integrated circuit is located on substrate 11;

[0155] A bulk acoustic wave actuator 12, located above the substrate 11 and having a vibration region 13; and

[0156] The liquid cavity 16 is located at least partially above the vibration region 13.

[0157] like Figure 8 As shown, the bulk acoustic wave driver 12 includes:

[0158] An acoustic reflective layer 121 is located on the upper side of the substrate 11;

[0159] The first electrode 122 is located on the upper side of the acoustic reflection layer 121, and the first electrode 122 is connected to the first conductive part 211 of the integrated circuit through the first interface part 1221.

[0160] A piezoelectric layer 123 is located at least partially above the first electrode 122;

[0161] The second electrode 124 is located above the piezoelectric layer 123 and is connected to the second conductive part 212 of the integrated circuit through the second interface 1241; wherein the first electrode 122, the piezoelectric layer 123 and the second electrode 124 at least partially overlap in a direction perpendicular to the substrate 11 to form the vibration region 13.

[0162] like Figure 1 and Figure 2 As shown, the acoustic droplet ejection device 10 further includes a liquid layer 14, which is at least partially located above the vibration region 13 of the bulk acoustic wave actuator 12. This liquid layer 14 can be formed during manufacturing or product shipment, or it can be formed after shipment when it is needed for use; this application is not limited thereto. Furthermore, as... Figure 2 As shown, the liquid layer 14 can be contained in the liquid cavity 16, but this application is not limited to this. For example, the liquid layer 14 can also be formed by liquid tension, as long as the liquid layer 14 covers the vibration region 13.

[0163] like Figure 1 and Figure 2 As shown, the integrated circuit can be referred to as an interconnect structure, which can be disposed on the substrate 11; a dielectric structure can be disposed on this interconnect structure. For example, as... Figure 2 As shown, the interconnect structure may include devices (e.g., conductive contacts 36, conductive holes 37, conductive lines 38, etc.) disposed in the dielectric layer 21 and / or devices (e.g., IC devices 34, etc.) disposed in the substrate 11, but this application is not limited thereto.

[0164] Therefore, controlling the droplet ejection device via an integrated circuit on the substrate is compatible with CMOS processes, and the arrayed driver control is flexible and compact. For example, a single driver can be controlled by an integrated circuit, or multiple drivers can be controlled by an integrated circuit. Furthermore, integration with CMOS circuits can reduce signal parasitics and wire interference effects in the circuit structure.

[0165] In some embodiments, such as Figure 8 As shown, the acoustic droplet ejection device 80 may further include

[0166] A passivation layer 15 is located above the second electrode 124. For example, the passivation layer 15 is located between the second electrode 124 and the liquid layer 14.

[0167] Therefore, the passivation layer can isolate the bulk acoustic wave actuator from the liquid, thus protecting the bulk acoustic wave actuator and improving the quality and service life of the device.

[0168] In some embodiments, the thickness of the passivation layer 15 is less than 200 nanometers.

[0169] Therefore, the passivation layer is relatively thin, which can reduce the impact on the performance of the bulk acoustic wave driver.

[0170] Furthermore, the passivation layer 15 can be further optimized to enhance its corrosion resistance, and its hydrophilic / hydrophobic properties facilitate liquid jetting. For example, the material of the passivation layer 15 can be an insulating material resistant to organic / inorganic corrosion, such as aluminum nitride, silicon carbide, silicon nitride, or silicon dioxide. The area of ​​the passivation layer 15 can be limited to covering the driver or can cover the entire wafer surface, providing a substrate for the subsequent fabrication of the flow channel and nozzle system.

[0171] like Figure 8 As shown, the liquid cavity 16 has a chamber 141 capable of accommodating the liquid layer 14 and a replenishment channel 161 capable of replenishing the liquid layer 14.

[0172] Therefore, through the replenishment channel, liquid can be replenished in a timely manner even during high-throughput spraying, effectively ensuring the stability of the liquid level height during spraying and enabling long-term spraying.

[0173] like Figure 8 As shown, the liquid cavity 16 has a nozzle 162 at a position corresponding to the vibration region 13. A liquid layer 14 can be formed in the chamber 141 within the liquid cavity 16. Through the vibration of the vibration region 13, droplets 17 are ejected from the nozzle 162. The liquid layer 14 can be replenished through the replenishment channel 161.

[0174] As a result, droplets are ejected from the nozzle, and the diameter of the ejected droplets is more uniform; and because the driver has low power consumption and low heat dissipation, there will be no nozzle clogging problem.

[0175] The structure of the acoustic droplet ejection device according to the embodiments of this application has been schematically described above. The principle and method of the acoustic droplet ejection device will be described below.

[0176] In some embodiments, the first electrode 122 (also referred to as the lower electrode or bottom electrode) and the second electrode 124 (also referred to as the upper electrode or top electrode) are connected to a signal generator (not shown in the figure, but refer to related technologies) via gold wire (or other conductive material). The signal generator applies a high-frequency pulse signal to the first electrode 122 and the second electrode 124, which can cause the piezoelectric layer 123 to generate mechanical vibration due to the inverse piezoelectric effect. The high-frequency mechanical vibration generates high-frequency sound waves.

[0177] Sound waves are prone to attenuation and leakage during transmission, resulting in a reduction in sound wave energy. Therefore, the sound reflection layer 121 can reflect sound waves, confining the sound wave energy to the inside of the actuator to the maximum extent. When the bulk acoustic wave actuator 12 acts on the liquid, a large amount of high-frequency sound waves leak into the liquid. Since the transmission speed of sound waves is different in different media, when the sound waves are transmitted into the liquid, they push the liquid to generate acoustic flow and cause attenuation. The expression for the attenuation coefficient β is:

[0178]

[0179] Among them, c L ρ is the speed of sound propagation in the liquid, ω is the frequency of the sound wave, ρ is the density of the liquid, and μ is the viscosity of the liquid. B This is the volume viscosity of the liquid. From the above formula, we can see that once the properties of the liquid are determined, the attenuation rate of sound waves propagating in the liquid is proportional to the square of the sound wave frequency.

[0180] The nonlinear attenuation of sound waves propagating in a liquid induces a volume force, the expression of which is:

[0181] F B =2ρβω 2 u 2 e -2βz

[0182] Where u is the velocity amplitude of the sound wave in the z-direction. The magnitude of the body force is positively correlated with the frequency of the sound wave; that is, the higher the frequency of the sound wave, the greater the body force generated. The decay rate of the body force is also positively correlated with the frequency.

[0183] In this embodiment, a bulk acoustic wave actuator 12 that generates high-frequency sound waves is used, typically with a frequency of 0.1 GHz to 5 GHz. According to the aforementioned volume force formula, this high-frequency bulk acoustic wave actuator 12 can generate a huge volume force, pushing the liquid to overcome surface tension. For example, as... Figure 3 As shown, liquid spikes may form under the action of volume forces, and droplets 17 are ejected from the liquid layer 14 at a certain ejection velocity. In addition, the acoustic reflector layer 121 is used to reflect sound waves, confining the sound wave energy to the inside of the driver to the maximum extent.

[0184] In the embodiments of the present application, the frequency f1 of the pulse signal can be determined according to the vibration frequency f2 of the used driver. For example, 0.9*f2 < f1 < 1.1*f2. The vibration frequency f2 of the driver is generally 0.1 GHz - 5 GHz. The duration t1 of the pulse signal is generally 1 us - 10 ms, and the period t2 of the pulse signal is generally more than 10 us. The period t2 is generally more than twice the duration t1 of the pulse signal. The liquid cavity is generally filled with water, ink or other fluids, and the thickness of the liquid layer is generally 10 um - 300 um.

[0185] According to the volume force formula, the viscosity of the liquid will affect the volume force. The greater the viscosity, the greater the volume force, but the greater the power required to drive the liquid with high viscosity to complete droplet ejection. At the same time, under the condition that other conditions remain unchanged, increasing the power can also increase the ejection speed of the droplets.

[0186] In some embodiments, one or more of the surface acoustic wave drivers may be provided on the substrate. For example, in the case where multiple surface acoustic wave drivers are included on the substrate, the multiple surface acoustic wave drivers are respectively located on the upper side of the substrate, and a predetermined distance is provided between two adjacent surface acoustic wave drivers.

[0187] Thus, a droplet ejection structure with an array arrangement of surface acoustic wave drivers can be formed, which is beneficial to the miniaturization of the product.

[0188] In some embodiments, for example, the first electrode and the second electrode of each surface acoustic wave driver 12 can be correspondingly connected to a group of signal generators, and each group of signal generators is respectively controlled to control the ejection state of the corresponding driver. For each surface acoustic wave driver 12, when a high-frequency signal is applied, droplets are ejected from its corresponding surface. In addition to individual control, high-frequency signals can also be applied to two or more drivers simultaneously to complete the ejection of multiple droplets.

[0189] For another example, the vibration frequency of the surface acoustic wave driver 12 is 2.4 GHz, the vibration region of the surface acoustic wave driver 12 is a pentagon, and the area of the pentagon is 1100 um 2 . The distance between two adjacent surface acoustic wave drivers 12 can be 1 mm. The liquid layer is, for example, conventional ink, and the thickness of the liquid layer is, for example, 150 microns.

[0190] The structure of the embodiments of the present application has been described above, but the present application is not limited thereto. The specific content of each device or component can also refer to the related art; in addition, devices or components not shown in Figures 1 to 8 can be added, or Figures 1 to 8 one or more devices or components in

[0191] The following describes the method of using the acoustic droplet ejection device with a replenishment structure according to the embodiments of this application.

[0192] This application also provides an acoustic droplet injection method with a replenishment structure, wherein the method uses the above-described acoustic droplet injection device. Figure 9 This is a schematic diagram of an acoustic droplet ejection method with a replenishing liquid structure according to an embodiment of this application, as shown below. Figure 9 As shown, the method includes:

[0193] Step 901: Apply a pulse signal to the first and second electrodes of the bulk acoustic wave driver in the acoustic droplet ejection device;

[0194] Step 902, ejecting droplets from the liquid layer of the acoustic droplet ejection device; and

[0195] Step 903: Replenish the liquid layer through the replenishment channel in the liquid chamber;

[0196] When the pulse signal is applied to the first electrode and the second electrode, the piezoelectric layer of the acoustic droplet ejection device vibrates in the vibration region and forms a sound wave. At least part of the sound wave is reflected by the acoustic reflection layer of the acoustic droplet ejection device and transmitted to the liquid layer. The sound wave is coupled into the liquid layer to generate a volume force, causing the liquid layer to eject the droplet.

[0197] Therefore, by using a replenishment channel, liquid can be replenished in a timely manner even during high-throughput spraying, effectively ensuring the stability of the liquid level height during spraying and enabling long-term spraying. By having the first electrode, piezoelectric layer, and second electrode at least partially overlap in a direction perpendicular to the substrate to form a vibration region, bulk acoustic waves propagate along the vertical direction and are reflected by an acoustic reflection layer. When in contact with the liquid layer, the high-frequency acoustic waves couple into the liquid layer, generating volume forces, thus concentrating the energy during liquid spraying and requiring lower spraying power. This structure allows for a smaller bulk acoustic wave actuator size and a higher throughput of sprayed droplets.

[0198] In some embodiments, when the sound waves are transmitted to the liquid layer, they push the liquid and cause attenuation, which induces volume forces and causes the liquid to overcome surface tension and form the droplets.

[0199] Therefore, droplet ejection is driven by the volume force generated by attenuation in a liquid environment.

[0200] In some embodiments, the droplets are ejected through a nozzle located in the liquid cavity corresponding to the vibration region.

[0201] As a result, the droplet diameter can be further precisely controlled, resulting in good uniformity.

[0202] In some embodiments, pulse signals can be applied to the first and second electrodes of the bulk acoustic wave driver in the acoustic droplet ejection device via an integrated circuit in the device.

[0203] Therefore, the droplet ejection device can be controlled by integrated circuits on the substrate, which is compatible with CMOS technology, and the driver control method after array is flexible and small in size.

[0204] The usage method of the embodiments of this application has been described above, but this application is not limited thereto. For example, the execution order between various operations can be appropriately adjusted, and other operations can be added or some operations can be removed. Those skilled in the art can make appropriate modifications based on the above content, and are not limited to the above-described embodiments. Figure 9 The records.

[0205] The manufacturing method of the acoustic droplet ejection device with a replenishment structure according to the embodiments of this application will be described below.

[0206] Figure 10 This is a schematic diagram of a method for manufacturing an acoustic droplet ejection device with a replenishing liquid structure according to an embodiment of this application, as shown below. Figure 10 As shown, the method includes:

[0207] Step 1001: Form a bulk acoustic wave actuator, the bulk acoustic wave actuator being located on the upper side of the substrate and having a vibration region;

[0208] Step 1002: Forming a liquid cavity, the liquid cavity being at least partially located above the bulk acoustic wave driver, the liquid cavity having a chamber for accommodating a liquid layer and a replenishment channel for replenishing the liquid layer.

[0209] The forming bulk acoustic wave driver includes:

[0210] Step 1011: Form an acoustic reflection layer on the upper side of the substrate;

[0211] Step 1012: A first electrode is formed on the upper side of the acoustic reflection layer;

[0212] Step 1013: Form a piezoelectric layer on the upper side of the first electrode; and

[0213] Step 1014: A second electrode is formed on the upper side of the piezoelectric layer; wherein the first electrode, the piezoelectric layer and the second electrode at least partially overlap in a direction perpendicular to the substrate to form the vibration region.

[0214] Therefore, by using a replenishment channel, liquid can be replenished in a timely manner even during high-throughput spraying, effectively ensuring the stability of the liquid level height during spraying and enabling long-term spraying. By having the first electrode, piezoelectric layer, and second electrode at least partially overlap in a direction perpendicular to the substrate to form a vibration region, bulk acoustic waves propagate along the vertical direction and are reflected by an acoustic reflection layer. When in contact with the liquid layer, the high-frequency acoustic waves couple into the liquid layer, generating volume forces, thus concentrating the energy during liquid spraying and requiring lower spraying power. This structure allows for a smaller size and higher droplet throughput in the bulk acoustic wave actuator. The bulk acoustic wave actuator can be fabricated using microelectromechanical systems (MEMS) technology and can be easily integrated with complementary metal-oxide-semiconductor (CMOS) technology.

[0215] In some embodiments, the method further includes forming a passivation layer between the second electrode and the liquid layer.

[0216] In some embodiments, forming the liquid cavity includes: forming a sacrificial layer on the bulk acoustic wave driver; forming the liquid cavity on the sacrificial layer; and releasing the sacrificial layer to form the replenishment channel and the chamber containing the liquid layer.

[0217] In some embodiments, the method further includes forming an integrated circuit located on the substrate.

[0218] In some embodiments, when a first electrode is formed on the upper side of the acoustic reflection layer, the first electrode is connected to a first conductive part of the integrated circuit through a first interface portion; when a second electrode is formed on the upper side of the piezoelectric layer, the second electrode is connected to a second conductive part of the integrated circuit through a second interface portion.

[0219] In some embodiments, one or more of the bulk acoustic wave drivers are formed on the substrate. For example, the plurality of bulk acoustic wave drivers are respectively located on the upper side of the substrate, and a predetermined distance is spaced between two adjacent bulk acoustic wave drivers.

[0220] The following is another example Figure 2 Taking the acoustic droplet ejection device 10 with a replenishing liquid structure shown as an example, the steps are illustrated below.

[0221] Figure 11 This is an example diagram illustrating the fabrication of an acoustic reflective layer according to an embodiment of this application. (See diagram below.) Figure 11 As shown, for example, an acoustic reflection layer 121 is prepared on a substrate 11, which is a Bragg reflection layer.

[0222] For example, the specific process of fabricating the acoustic reflector layer 121 includes: sequentially and alternately depositing a five-layer structure of SiO2-Mo-SiO2-Mo-SiO2 on a silicon substrate. The three SiO2 layers are all grown as 0.65 μm thick films using chemical vapor deposition, while the two Mo layers are grown as 0.64 μm thick films using physical vapor deposition. The acoustic reflector layer can also be composed of other materials with different acoustic impedances, such as aluminum nitride and molybdenum, or aluminum nitride and tungsten. Alternatively, an air chamber can be used as the acoustic reflector layer structure.

[0223] Figure 12 This is an example diagram of the manufacturing of the first electrode according to an embodiment of this application; Figure 13 This is an example diagram of the fabrication of a piezoelectric layer according to an embodiment of this application; Figure 14 This is an example diagram illustrating the fabrication of the second electrode according to an embodiment of this application. (See diagram below.) Figures 12 to 14 As shown, for example, a sandwich structure unit array of bottom electrode-piezoelectric layer-top electrode of bulk acoustic wave driver 12 can be fabricated on acoustic reflection layer 121.

[0224] like Figure 12 As shown, for example, a molybdenum thin film with a thickness of 0.17 micrometers is grown using physical vapor deposition as the first electrode 122. Figure 13 As shown, for example, a 1.1-micrometer-thick aluminum nitride film is grown above the first electrode as a piezoelectric layer 123 using physical vapor deposition. Figure 14 As shown, for example, a molybdenum film with a thickness of 0.15 micrometers is grown as the second electrode 124 using the same deposition method as the first electrode 122.

[0225] Figure 15 This is an example diagram illustrating the fabrication of a passivation layer according to an embodiment of this application. For example... Figure 15 As shown, for example, a layer of SiO2 with a thickness of 0.1 micrometers can be deposited on top of the second electrode as a passivation layer 15 to protect the bulk acoustic wave driver 12.

[0226] In some embodiments, the area of ​​the bulk acoustic wave driver can be patterned to a specific shape, for example... Figure 1 or Figure 4 The pentagon shown. Specifically, for example, it can be completed using a mask, and the specific shape of the above part can be etched using a dry etching technique.

[0227] Figure 16 This is an example diagram of a patterned device according to an embodiment of this application. For simplicity, Figure 16 The following figures omit the passivation layer 15 and other devices, but this application is not limited thereto.

[0228] The following example illustrates the fabrication of the fluid replenishment structure and nozzle structure. The chamber and flow channel structures can be deposited at specific locations using a mask by releasing a sacrificial layer. The nozzle and fluid replenishment structures are then fabricated through an etching process, and finally, the sacrificial layer is released to obtain the final fluid replenishment and nozzle structures.

[0229] Figure 17 This is an example diagram of an etching fluid replenishment channel according to an embodiment of this application. For example, as... Figure 17 As shown, a liquid replenishment channel 161 of a certain thickness is etched on the surface of a silicon wafer with a driver using a mask. The depth is typically a few micrometers to hundreds of micrometers, and the diameter is a few micrometers to tens of micrometers.

[0230] Figure 18 This is an example diagram illustrating the preparation of the sacrificial layer according to an embodiment of this application. For example... Figure 18 As shown, a sacrificial layer material, such as silicon oxide, PSG, silicon, metal, or polymer, can be deposited on the wafer. Chemical mechanical polishing and other methods can be used to flatten the surface of the sacrificial layer, facilitating subsequent applications.

[0231] Figure 19 This is an example diagram of photolithography performed on the sacrificial layer according to an embodiment of this application. Figure 19 As shown, by using a photomask to perform photolithography on the sacrificial layer material, the shape and area of ​​the desired chamber can be obtained.

[0232] Figure 20 This is an example diagram illustrating the preparation of a liquid cavity according to an embodiment of this application. Figure 20 As shown, a structural layer can be grown on the surface of the etched sacrificial layer as a flow channel and chamber. The material of this structural layer is, for example, aluminum nitride, silicon carbide, silicon nitride, silicon oxide, silicon, etc.

[0233] Figure 21 This is an example diagram of the fabrication of a nozzle according to an embodiment of this application. For example, the nozzle structure can be etched using a mask.

[0234] Figure 22 This is an example diagram illustrating the fabrication of a replenishment channel and chamber according to an embodiment of this application. For example, etching can be performed on the back side of the wafer. Then, the sacrificial layer can be released to obtain the replenishment channel and chamber, thereby fabricating a structure as described above. Figure 2 The acoustic droplet ejection device 10 shown has a liquid replenishment structure.

[0235] Figures 11 to 22 The manufacturing process of the acoustic droplet ejection device 10 with a liquid replenishment structure has been illustrated, but this application is not limited thereto. Furthermore, a similar manufacturing process can be used for the acoustic droplet ejection device 80 with a liquid replenishment structure.

[0236] The following is another example Figure 8Taking the acoustic droplet ejection device 80 with a replenishing liquid structure shown as an example, the steps are illustrated by way of example.

[0237] Figure 23 This is an example diagram illustrating the fabrication of an acoustic reflective layer according to an embodiment of this application. (See diagram below.) Figure 23 As shown, for example, an acoustic reflection layer 121 is fabricated on the dielectric layer 21, which is a Bragg reflection layer. For the fabrication method of the dielectric layer 21, please refer to relevant technologies; it will not be elaborated here.

[0238] For example, the specific process of fabricating the acoustic reflector layer 121 includes: sequentially and alternately depositing a five-layer structure of SiO2-Mo-SiO2-Mo-SiO2 on a silicon substrate. The three SiO2 layers are all grown as 0.65 μm thick films using chemical vapor deposition, while the two Mo layers are grown as 0.64 μm thick films using physical vapor deposition. The acoustic reflector layer can also be composed of other materials with different acoustic impedances, such as aluminum nitride and molybdenum, or aluminum nitride and tungsten. Alternatively, an air chamber can be used as the acoustic reflector layer structure.

[0239] Figure 24 This is an example diagram of the manufacturing of the first electrode according to an embodiment of this application; Figure 25 This is another example diagram of the manufacturing of the first electrode according to an embodiment of this application; Figure 26 This is an example diagram of the fabrication of a piezoelectric layer according to an embodiment of this application; Figure 27 This is an example diagram of the manufacturing of a dielectric layer according to an embodiment of this application; Figure 28 This is an example diagram of the manufacturing of the second electrode according to an embodiment of this application; Figure 29 This is another example diagram illustrating the fabrication of the second electrode according to an embodiment of this application. (See diagram below.) Figures 24 to 29 As shown, for example, a sandwich structure unit array of bottom electrode-piezoelectric layer-top electrode of bulk acoustic wave driver 12 can be fabricated on acoustic reflection layer 121.

[0240] like Figure 24 As shown, dry etching or wet etching can be used to etch the interface portion 701 of the bottom electrode on the dielectric layers 22, 23 and the acoustic reflection layer 121. Figure 25 As shown, a thin film can be grown from a metallic material such as Mo or Al using physical vapor deposition to serve as the bottom electrode (first electrode 122). Figure 25 As shown, the first electrode 122 is connected to the first conductive part 211 of the integrated circuit through the first interface part 1221.

[0241] like Figure 26 As shown, for example, a 1.1 μm thick aluminum nitride film is grown above the bottom electrode as a piezoelectric layer 123 using physical vapor deposition. Figure 27As shown, a layer of silicon dioxide or other insulating material can be deposited as a dielectric layer 24 on the bottom electrode and the portion where the piezoelectric layer 123 is not deposited, using a physical vapor deposition method.

[0242] like Figure 28 As shown, dry etching or wet etching can be used to etch the interface portion 702 of the top electrode onto dielectric layers 22 and 23, acoustic reflection layer 121, and dielectric layer 24. Figure 29 As shown, aluminum, molybdenum, tungsten, copper, and other metallic materials can be selected, and a thin film can be grown using physical vapor deposition as the top electrode (second electrode 124). Figure 29 As shown, the second electrode 124 is connected to the second conductive part 212 of the integrated circuit through the second interface part 1241.

[0243] Figure 30 This is an example diagram illustrating the fabrication of a passivation layer according to an embodiment of this application. For example... Figure 30 As shown, for example, a 0.1-micrometer-thick layer of SiO2 can be deposited on top of the second electrode using chemical vapor deposition as a passivation layer 15 to protect the bulk acoustic wave actuator 12. The material of the passivation layer 15 can be silicon dioxide, aluminum nitride, silicon nitride, silicon carbide, etc.

[0244] The following example illustrates the fabrication of the fluid replenishment structure and nozzle structure. The chamber and flow channel structures can be deposited at specific locations using a mask by releasing a sacrificial layer. The nozzle and fluid replenishment structures are then fabricated through an etching process, and finally, the sacrificial layer is released to obtain the final fluid replenishment and nozzle structures.

[0245] Figure 31 This is an example diagram of an etching fluid replenishment channel according to an embodiment of this application. For example, as... Figure 31 As shown, on the surface of the silicon wafer with the driver, a liquid replenishment channel 161 of a certain thickness is etched using a mask. Its depth is typically from a few micrometers to several hundred micrometers, and its diameter is from a few micrometers to tens of micrometers.

[0246] Figure 32 This is an example diagram illustrating the preparation of the sacrificial layer according to an embodiment of this application. For example... Figure 32 As shown, a sacrificial layer material, such as silicon oxide, PSG, silicon, metal, or polymer, can be deposited on the wafer. Chemical mechanical polishing (CMP) and other methods can be used to flatten the surface of the sacrificial layer, facilitating subsequent applications. Figure 32 As shown, a photolithography technique can be used to lithographically model the sacrificial layer material to obtain the desired shape and area of ​​the cavity.

[0247] Figure 33 This is an example diagram illustrating the preparation of a liquid cavity according to an embodiment of this application. Figure 33As shown, a structural layer can be grown on the surface of the etched sacrificial layer as a flow channel and chamber. The material of this structural layer is, for example, aluminum nitride, silicon carbide, silicon nitride, silicon oxide, silicon, etc.

[0248] Figure 34 This is an example diagram of the fabrication of a nozzle according to an embodiment of this application. For example, the nozzle structure can be etched using a mask.

[0249] Figure 35 This is an example diagram illustrating the fabrication of a fluid replenishment channel according to an embodiment of this application. For example, etching can be performed on the back side of the wafer. Then, the sacrificial layer can be released to obtain the fluid replenishment channel and chamber, thereby fabricating a structure as described above. Figure 8 The acoustic droplet ejection device 80 shown has a liquid replenishment structure.

[0250] Figures 23 to 35 The manufacturing process of an acoustic droplet ejection device 80 with a replenishment structure is illustrated by way of example, but this application is not limited thereto.

[0251] The above embodiments are merely illustrative examples of embodiments of this application, but this application is not limited thereto, and appropriate modifications can be made based on the above embodiments. For example, the above embodiments can be used alone, or one or more of the above embodiments can be combined.

[0252] In this embodiment, all manufacturing processes of the bulk acoustic wave actuator, including the substrate fabrication (including the liquid replenishment structure and nozzle structure), can be standard MEMS fabrication processes, compatible with CMOS processes; the vibration region area of ​​the bulk acoustic wave actuator is typically 10µm. 2 -20000um 2 The size of the driver itself is much smaller than that of surface acoustic wave, ultrasonic and other acoustic wave devices, so more drivers can be arrayed per unit area.

[0253] Furthermore, the sound waves from the bulk acoustic wave actuator propagate vertically, resulting in more concentrated energy in the vertical direction compared to surface acoustic waves, thus requiring less power for droplet ejection. The smaller the pulse signal width and period, the more droplets can be ejected per second. Therefore, by adjusting the pulse signal width and period, thousands or even tens of thousands of droplets can be ejected per second. The microchannel liquid replenishment structure ensures a highly stable liquid surface, preventing satellite droplets and resulting in highly uniform droplet ejection under the nozzle's action. Due to the actuator's low power consumption and minimal heat dissipation, nozzle clogging is eliminated, making it a promising candidate for applications such as inkjet printing and 3D biomanufacturing.

[0254] This application also provides an electrical product having the acoustic droplet ejection device described above. This electrical product includes, for example, inkjet printers, 3D printers, etc., but this application is not limited thereto.

[0255] It is worth noting that the above description is merely illustrative of the embodiments of this application, but the embodiments of this application are not limited thereto, and appropriate modifications can be made based on the above embodiments. Furthermore, the above description is merely illustrative of the various components, but the embodiments of this application are not limited thereto, and the specific content of each component can be referred to related technologies; in addition, components not shown in the figures can be added, or one or more components in the figures can be removed.

[0256] The embodiments of this application have been described above with reference to specific implementation methods. However, those skilled in the art should understand that these descriptions are exemplary and not intended to limit the scope of protection of the embodiments of this application. Those skilled in the art can make various modifications and variations to the embodiments of this application based on the spirit and principles of the embodiments, and these modifications and variations are also within the scope of the embodiments of this application.

[0257] Preferred embodiments of the present application have been described above with reference to the accompanying drawings. Many features and advantages of these embodiments are apparent from this detailed description, and therefore the appended claims are intended to cover all such features and advantages falling within the true spirit and scope of these embodiments. Furthermore, since many modifications and alterations will readily occur to those skilled in the art, the embodiments of the present application are not intended to be limited to the precise structures and operations illustrated and described, but rather to encompass all suitable modifications and equivalents falling within their scope.

Claims

1. An acoustic droplet ejection device with a liquid replenishment structure, characterized in that, The device includes: Substrate; A bulk acoustic wave actuator, located on the upper side of the substrate and having a vibration region; and A liquid cavity, at least partially located above the bulk acoustic wave driver, has a chamber capable of containing a liquid layer and a replenishment channel capable of replenishing the liquid layer. The replenishment channel penetrates the substrate and communicates with the chamber to replenish the chamber from outside the liquid cavity. The height of the chamber in a direction perpendicular to the substrate is 1 micrometer to 300 micrometers. The bulk acoustic wave driver includes: An acoustic reflective layer is located on the upper side of the substrate; The first electrode is located on the upper side of the acoustic reflective layer; A piezoelectric layer, at least partially located above the first electrode; A second electrode is located above the piezoelectric layer; wherein the first electrode, the piezoelectric layer, and the second electrode at least partially overlap in a direction perpendicular to the substrate to form the vibration region. When a pulse signal is applied to the first and second electrodes, the piezoelectric layer vibrates in the vibration region and generates sound waves. At least a portion of the sound waves are reflected by the acoustic reflection layer and transmitted to the liquid layer. The sound waves couple into the liquid layer to generate volume forces, causing the liquid layer to eject droplets. The liquid cavity has a nozzle at a position corresponding to the vibration region. The nozzle is circular, elliptical, or polygonal in shape. When viewed from a direction perpendicular to the substrate, the positions of the nozzle and the vibration region are concentrically distributed.

2. The apparatus according to claim 1, characterized in that, The device further includes: A passivation layer is located between the second electrode and the liquid layer.

3. The apparatus according to claim 1, characterized in that, The acoustic reflective layer includes a baffle layer structure and / or an air cavity structure.

4. The apparatus according to claim 1, characterized in that, The device further includes: An integrated circuit is located on the upper side of the substrate; and the bulk acoustic wave driver is located on the upper side of the integrated circuit.

5. The apparatus according to claim 4, characterized in that, The first electrode is connected to the first conductive part of the integrated circuit through a first interface; the second electrode is connected to the second conductive part of the integrated circuit through a second interface.

6. The apparatus according to claim 1, characterized in that, One or more of the bulk acoustic wave drivers are included on the substrate.

7. The apparatus according to claim 6, characterized in that, Multiple bulk acoustic wave actuators are located on the upper side of the substrate, and a predetermined distance is spaced between two adjacent bulk acoustic wave actuators.

8. The apparatus according to any one of claims 1 to 7, characterized in that, When the sound waves travel to the liquid layer, they push the liquid and cause attenuation. This attenuation induces volume forces, causing the liquid to overcome surface tension and form droplets.

9. The apparatus according to claim 8, characterized in that, The droplets are ejected through a nozzle located in the liquid cavity at a position corresponding to the vibration region.

10. The apparatus according to claim 8, characterized in that, Through the integrated circuit in the acoustic droplet ejection device, pulse signals are applied to the first and second electrodes of the bulk acoustic wave driver in the acoustic droplet ejection device.

11. An acoustic droplet ejection method with a replenishing liquid structure, characterized in that, The method uses the acoustic droplet ejection device as described in any one of claims 1 to 7, the method comprising: A pulse signal is applied to the first and second electrodes of the bulk acoustic wave driver in the acoustic droplet ejection device; Droplets are ejected from the liquid layer of the acoustic droplet ejection device; and The liquid layer is replenished through the replenishment channel within the liquid chamber; When the pulse signal is applied to the first electrode and the second electrode, the piezoelectric layer of the acoustic droplet ejection device vibrates in the vibration region and forms a sound wave. At least part of the sound wave is reflected by the acoustic reflection layer of the acoustic droplet ejection device and transmitted to the liquid layer. The sound wave is coupled into the liquid layer to generate a volume force, causing the liquid layer to eject the droplet.

12. The method according to claim 11, characterized in that, When the sound waves are transmitted to the liquid layer, they push the liquid and cause attenuation. The attenuation causes volume forces, which cause the liquid to overcome surface tension and form droplets.

13. The method according to claim 11, characterized in that, The droplets are ejected through a nozzle located in the liquid cavity at a position corresponding to the vibration region.

14. The method according to claim 11, characterized in that, A pulse signal is applied to the first and second electrodes of the bulk acoustic wave driver in the acoustic droplet ejection device via the integrated circuit in the device.

15. A method for manufacturing an acoustic droplet ejection device with a liquid replenishment structure, characterized in that, The method includes: A bulk acoustic wave actuator is formed, the bulk acoustic wave actuator being located on the upper side of the substrate and having a vibration region; and A liquid cavity is formed, at least partially located on the upper side of the bulk acoustic wave driver. The liquid cavity has a chamber capable of containing a liquid layer and a replenishment channel capable of replenishing the liquid layer. The replenishment channel penetrates the substrate and communicates with the chamber to replenish the chamber from the outside. The height of the chamber in the direction perpendicular to the substrate is 1 micrometer to 300 micrometers. The liquid cavity has a nozzle at a position corresponding to the vibration region. The nozzle is circular, elliptical, or polygonal in shape. When viewed from the direction perpendicular to the substrate, the positions of the nozzle and the vibration region are concentrically distributed. The forming bulk acoustic wave driver includes: An acoustic reflection layer is formed on the upper side of the substrate; A first electrode is formed on the upper side of the acoustic reflective layer; A piezoelectric layer is formed on the upper side of the first electrode; and A second electrode is formed on the upper side of the piezoelectric layer; wherein the first electrode, the piezoelectric layer and the second electrode at least partially overlap in a direction perpendicular to the substrate to form the vibration region.

16. The method according to claim 15, characterized in that, The method further includes: A passivation layer is formed between the second electrode and the liquid layer.

17. The method according to claim 15, characterized in that, The formation of the liquid cavity includes: A sacrificial layer is formed on the bulk acoustic wave driver; The liquid cavity is formed on the sacrificial layer; and The sacrificial layer is released to form the replenishment channel and the chamber that contains the liquid layer.

18. The method according to claim 15, characterized in that, The method further includes: An integrated circuit is formed on the substrate.

19. The method according to claim 18, characterized in that, When a first electrode is formed on the upper side of the acoustic reflection layer, the first electrode is connected to the first conductive part of the integrated circuit through a first interface portion; When a second electrode is formed on the upper side of the piezoelectric layer, the second electrode is connected to the second conductive part of the integrated circuit through a second interface portion.

20. The method according to claim 15, characterized in that, One or more of the bulk acoustic wave drivers are formed on the substrate.

21. The method according to claim 20, characterized in that, Multiple bulk acoustic wave actuators are located on the upper side of the substrate, and a predetermined distance is spaced between two adjacent bulk acoustic wave actuators.

22. An electrical product, characterized in that, The electrical product has an acoustic droplet injection device with a replenishing structure as described in any one of claims 1 to 10.

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