Acoustic droplet ejection method, apparatus and manufacturing method controlled by integrated circuit

Abstract

Embodiments of the present application provide an acoustic droplet ejection method and device controlled by an integrated circuit and a manufacturing method thereof. The device comprises a substrate, an integrated circuit on the substrate, and a bulk acoustic wave driver on the upper side of the substrate and having a vibration region. In the embodiments of the present application, the droplet ejection device is controlled by the integrated circuit on the substrate, which is compatible with CMOS technology, and the driver control mode after the array is flexible and the size is small.

Description

Technical Field

[0001] This application relates to the field of electronic technology, and in particular to an integrated circuit-controlled acoustic droplet ejection method, apparatus, and manufacturing method thereof. 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 the jetting system of this droplet ejection device is controlled by external circuitry that cannot be integrated with surface acoustic wave (SAW) devices, thus making it incompatible with CMOS technology. Furthermore, the control method of the driver after arraying is limited and the size is large. In addition, 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 flux of ejected droplets is low; and so on. Summary of the Invention

[0006] To address at least one of the aforementioned problems or other similar issues, embodiments of this application provide an integrated circuit-controlled acoustic droplet ejection method, apparatus, and manufacturing method thereof.

[0007] According to a first aspect of the embodiments of this application, an integrated circuit-controlled acoustic droplet ejection device is provided, comprising:

[0008] Substrate;

[0009] Integrated circuit, which is located on the substrate; and

[0010] A bulk acoustic wave actuator, which is located on the upper side of the substrate and has a vibration region;

[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 reflection layer, and the first electrode is connected to the first conductive part of the integrated circuit through the first interface portion;

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

[0015] The second electrode is located on the upper side of the piezoelectric layer and is connected to the second conductive part of the integrated circuit through a second interface portion; 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] According to a second aspect of the embodiments of this application, the apparatus further includes:

[0017] A liquid layer, at least partially located above the vibration region of the bulk acoustic wave actuator.

[0018] Therefore, controlling the droplet ejection device via an integrated circuit on the substrate is compatible with CMOS technology, and the array-mounted driver offers flexible control and a small size. 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 vertically and are reflected by an acoustic reflection layer. Upon contact with the liquid layer, the high-frequency acoustic waves couple into the liquid layer, generating volume forces, thus concentrating the energy during liquid ejection and requiring lower ejection power. Furthermore, the droplet diameter can be precisely controlled, the droplet ejection direction is vertically upward, and the throughput of ejected droplets is high.

[0019] According to a third aspect of the embodiments of this application, the apparatus further includes:

[0020] A passivation layer is located on the upper side of the second electrode.

[0021] This isolates the bulk acoustic wave actuator from the liquid, protecting it and thus improving the quality and lifespan of the device.

[0022] According to a fourth aspect of the embodiments of this application, the acoustic reflective layer includes a baffle layer structure and / or an air cavity structure.

[0023] According to a fifth aspect of the embodiments of this application, the area of ​​the vibration region of the bulk acoustic wave actuator is from 10 square micrometers to 20,000 square micrometers.

[0024] According to a sixth aspect of the embodiments of this application, the thickness of the liquid layer is from 1 micrometer to 1 millimeter.

[0025] According to a seventh aspect of the embodiments of this application, the vibration frequency of the bulk acoustic wave driver is from 0.1 GHz to 5 GHz.

[0026] As a result, the actuator is smaller in size, allowing for the arraying of more structures per unit area; and the pulse signal applied by the actuator has a shorter period, enabling the ejection of thousands or even tens of thousands of droplets per second, thus resulting in higher throughput.

[0027] According to an eighth aspect of the embodiments of this application, the distance between the substrate and the bulk acoustic wave driver does not exceed 2 mm.

[0028] According to a ninth aspect of the present application, one or more of the bulk acoustic wave drivers are included on the substrate, wherein at least one bulk acoustic wave driver is controlled by the integrated circuit to perform droplet ejection.

[0029] According to a tenth aspect of the present application, a plurality of bulk acoustic wave actuators are respectively located on the upper side of the dielectric layer, and a predetermined distance is spaced between two adjacent bulk acoustic wave actuators.

[0030] Therefore, the droplet jet structure of the bulk acoustic wave actuator, which can be arranged in an array, is beneficial for product miniaturization.

[0031] According to the eleventh aspect of the embodiments of this application, the distance between two independently controlled bulk acoustic wave drivers does not exceed 100 micrometers.

[0032] According to a twelfth aspect of the present application, the integrated circuit includes transistor devices and interconnect structures disposed in or on the substrate.

[0033] According to a thirteenth aspect of the present application, when a pulse signal is applied to the first electrode and the second electrode through the integrated circuit, the piezoelectric layer vibrates in the vibration region and forms a sound wave. At least a portion of the sound wave is reflected by the acoustic reflection layer 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 droplets.

[0034] According to a fourteenth 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 the volume force and causing the liquid to overcome the surface tension to form the droplet.

[0035] According to a fifteenth aspect of the present application, an integrated circuit-controlled acoustic droplet ejection method is provided, the method using the above-described acoustic droplet ejection device, the method comprising:

[0036] 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; and

[0037] Droplets are ejected from the liquid layer of the acoustic droplet ejection device;

[0038] 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.

[0039] Therefore, controlling the droplet ejection device via an integrated circuit on the substrate is compatible with CMOS technology, and the array-mounted driver offers flexible control and a small size. 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 vertically and are reflected by an acoustic reflection layer. Upon contact with the liquid layer, the high-frequency acoustic waves couple into the liquid layer, generating volume forces, thus concentrating the energy during liquid ejection and requiring lower ejection power. Furthermore, the droplet diameter can be precisely controlled, the droplet ejection direction is vertically upward, and the throughput of ejected droplets is high.

[0040] 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.

[0041] Therefore, droplet ejection is driven by the volume force generated by attenuation in a liquid environment.

[0042] According to the seventeenth aspect of the embodiments of this application, a method for manufacturing an integrated circuit-controlled acoustic droplet ejection device is provided, comprising:

[0043] An integrated circuit is formed, wherein the integrated circuit is located on the upper side of the substrate;

[0044] 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;

[0045] The forming bulk acoustic wave driver includes:

[0046] An acoustic reflection layer is formed on the upper side of the substrate;

[0047] A first electrode is formed on the upper side of the acoustic reflection layer, and the first electrode is connected to the first conductive part of the integrated circuit through a first interface portion;

[0048] A piezoelectric layer is formed on the upper side of the first electrode; and

[0049] A second electrode is formed on the upper side of the piezoelectric layer, and the second electrode is connected to the second conductive part of the integrated circuit through a second interface portion; 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.

[0050] According to the eighteenth aspect of the embodiments of this application, the method further includes:

[0051] A liquid layer is formed, at least a portion of which is located above the vibration region of the bulk acoustic wave driver.

[0052] Therefore, bulk acoustic wave actuators can be fabricated using microelectromechanical systems (MEMS) technology and easily integrated with complementary metal-oxide-semiconductor (CMOS) technology. The arrayed actuators offer flexible control and a compact size. By forming a vibration region through at least partial overlap of the first electrode, piezoelectric layer, and second electrode in a direction perpendicular to the substrate, bulk acoustic waves propagate vertically and are reflected by an acoustic reflection layer. Upon contact with the liquid layer, high-frequency acoustic waves couple into the liquid layer, generating volume forces, thus concentrating the energy during liquid ejection and requiring lower ejection power. Furthermore, the droplet diameter can be precisely controlled, the droplet ejection direction is vertically upward, and the flux of ejected droplets is high.

[0053] According to a nineteenth aspect of the embodiments of this application, the method further includes:

[0054] A passivation layer is formed on the upper side of the second electrode.

[0055] According to a twentieth aspect of the embodiments of this application, one or more of the bulk acoustic wave drivers are formed on the substrate.

[0056] According to a twenty-first 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.

[0057] According to a twenty-second aspect of the present application, an electrical product is provided, the electrical product having the acoustic droplet ejection device as described above.

[0058] One of the beneficial effects of this application's embodiments is that controlling the droplet ejection device via an integrated circuit on the substrate is compatible with CMOS technology, and the array-mounted driver offers flexible control and a small size. 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 vertically and are reflected by an acoustic reflection layer. Upon contact with the liquid layer, high-frequency acoustic waves couple into the liquid layer, generating volume forces, thus concentrating the energy during liquid ejection and requiring lower ejection power. Furthermore, the droplet diameter can be precisely controlled, the droplet ejection direction is vertically upward, and the throughput of ejected droplets is high.

[0059] 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.

[0060] 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.

[0061] 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

[0062] 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:

[0063] Figure 1 This is a schematic diagram of an integrated circuit-controlled acoustic droplet ejection device according to an embodiment of this application;

[0064] Figure 2 This is a cross-sectional view of an integrated circuit-controlled acoustic droplet ejection device according to an embodiment of this application;

[0065] Figure 3 This is a schematic diagram of the Bragg reflector layer according to an embodiment of this application;

[0066] Figure 4 This is a schematic diagram of an integrated circuit-controlled acoustic droplet ejection method according to an embodiment of this application;

[0067] Figure 5 This is a schematic diagram of a method for manufacturing an integrated circuit-controlled acoustic droplet ejection device according to an embodiment of this application;

[0068] Figure 6This is an example diagram of the fabrication of an acoustic reflective layer according to an embodiment of this application;

[0069] Figure 7 This is an example diagram of the manufacturing of the first electrode according to an embodiment of this application;

[0070] Figure 8 This is another example diagram of the manufacturing of the first electrode according to an embodiment of this application;

[0071] Figure 9 This is an example diagram of the fabrication of a piezoelectric layer according to an embodiment of this application;

[0072] Figure 10 This is an example diagram of the manufacturing of a dielectric layer according to an embodiment of this application;

[0073] Figure 11 This is an example diagram of the manufacturing of the second electrode according to an embodiment of this application;

[0074] Figure 12 This is another example diagram of the manufacturing of the second electrode according to an embodiment of this application;

[0075] Figure 13 This is an example diagram of the fabrication of the passivation layer according to an embodiment of this application. Detailed Implementation

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] The embodiments of this application will now be described with reference to the accompanying drawings.

[0081] 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. (See diagram below.) Figure 1 and Figure 2 As shown, the acoustic droplet ejection device 10 includes:

[0082] Substrate 11;

[0083] Integrated circuit, which is located on substrate 11;

[0084] A bulk acoustic wave driver 12 is located on the upper side of the substrate 11 and has a vibration region 13.

[0085] like Figure 1 and Figure 2 As shown, the bulk acoustic wave driver 12 includes:

[0086] An acoustic reflective layer 121 is located on the upper side of the substrate 11;

[0087] 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.

[0088] A piezoelectric layer 123 is located at least partially above the first electrode 122;

[0089] 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.

[0090] like Figure 1 and Figure 2As 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.

[0091] like Figure 1 and Figure 2 As shown, the integrated circuit includes transistor devices (such as IC device 34) and interconnect structures disposed on the substrate 11. The interconnect structures may be disposed on the substrate 11. The interconnect structures may include devices (such as conductive contacts 36, conductive holes 37, conductive lines 38, etc.) disposed in the dielectric layer 21, but this application is not limited thereto.

[0092] 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.

[0093] By forming a vibration region through at least partial overlap of the first electrode, piezoelectric layer, and second electrode in a direction perpendicular to the substrate, bulk acoustic waves propagate in the vertical direction and are reflected by the acoustic reflection layer. Upon contact with the liquid layer, high-frequency acoustic waves couple into the liquid layer to generate volume forces, thereby concentrating the energy during liquid ejection and requiring lower ejection power. Furthermore, the droplet diameter can be precisely controlled, the droplet ejection direction is vertically upward, and the flux of ejected droplets is high.

[0094] 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.

[0095] The liquid layer 14 is placed inside the liquid cavity 16, which can be made of organic or inorganic materials such as metal, glass, or PDMS. The liquid layer 14 can contain water, ink, or other liquids. The liquid layer 14 can be formed only when in use, for example, by injecting liquid into the chamber within the liquid cavity 16; however, this application is not limited thereto.

[0096] In some embodiments, such as Figure 2 As shown, the acoustic droplet ejection device 10 may further include

[0097] 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.

[0098] 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.

[0099] In some embodiments, the thickness of the passivation layer 15 is less than 200 nanometers.

[0100] Therefore, the passivation layer is relatively thin, which can reduce the impact on the performance of the bulk acoustic wave driver.

[0101] 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.

[0102] 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 may also be used.

[0103] Figure 3 This is a schematic diagram of a Bragg reflector layer 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 3 (as shown in 301) and 0.64 micrometers of molybdenum (as shown in 301) Figure 3 The Bragg reflector layer is formed by sequentially depositing (as shown in 302). 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.

[0104] 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.

[0105] 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.

[0106] In some embodiments, the vibration frequency of the bulk acoustic wave driver is from 0.1 GHz to 5 GHz.

[0107] 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.

[0108] 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.

[0109] In some embodiments, the distance between the substrate 11 and the bulk acoustic wave driver 12 does not exceed 2 mm. For example, the thickness of the dielectric layer 21 does not exceed 2 mm.

[0110] 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 according to the embodiments of this application will be described below.

[0111] In some embodiments, such as Figure 2 As shown, 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 respectively connected to the integrated circuit through an interface. Through the integrated circuit, the signal generator can apply a high-frequency pulse signal to the first electrode 122 and the second electrode 124, causing the piezoelectric layer 123 to generate mechanical vibration due to the inverse piezoelectric effect, and the high-frequency mechanical vibration generates high-frequency sound waves.

[0112] 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:

[0113]

[0114] 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.

[0115] The nonlinear attenuation of sound waves propagating in a liquid induces a volume force, the expression of which is:

[0116] F B =2ρβω 2 u 2 e -2βz

[0117] 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.

[0118] In this embodiment, a bulk acoustic wave actuator 12 that generates high-frequency sound waves is used, typically between 0.1 GHz and 5 GHz. According to the aforementioned volume force formula, this high-frequency bulk acoustic wave actuator 12 can generate a huge volume force, propelling the liquid to overcome surface tension. For example, under the action of the volume force, liquid spikes may be formed, and droplets may be ejected from the liquid layer 14 at a certain ejection velocity.

[0119] Furthermore, the acoustic reflector layer 121 is used to reflect sound waves, confining the sound wave energy to the inside of the actuator to the maximum extent. By changing the duration of the pulse signal applied between the first electrode 122 and the second electrode 124, the duration of the volume force can be changed, and the diameter of the droplets generated in the liquid layer 14 can be controlled due to the different durations. By increasing the power of the high-frequency pulse signal, the ejection velocity of the droplets can be increased.

[0120] In some embodiments, the frequency f1 of the pulse signal can be determined according to the vibration frequency f2 of the driver used, 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. Generally, the period t2 is more than twice the duration t1 of the pulse signal. The liquid chamber generally contains water, ink or other fluids, and the thickness of the liquid layer is generally 10 um - 300 um.

[0121] 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.

[0122] In some embodiments, one or more of the bulk acoustic wave drivers are included on the substrate. For example, in the case where a plurality of bulk acoustic wave drivers are included on the substrate, the plurality of bulk acoustic wave drivers are respectively located on the upper side of the substrate, and a predetermined distance is provided between two adjacent bulk acoustic wave drivers.

[0123] Thus, a droplet ejection structure with an array arrangement of bulk acoustic wave drivers can be formed, which is beneficial to the miniaturization of the product.

[0124] In some embodiments, in the case where a plurality of bulk acoustic wave drivers are included on the substrate, at least one bulk acoustic wave driver is controlled by the integrated circuit to perform droplet ejection.

[0125] For example, the first electrode and the second electrode of each bulk acoustic wave driver 12 can be correspondingly connected to a group of signal generators through the integrated circuit, and each group of signal generators is respectively controlled to control the ejection state of the corresponding driver. For each bulk 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 simultaneously applied to two or more drivers through the integrated circuit to complete the ejection of multiple droplets.

[0126] In some embodiments, the distance between two independently controlled bulk acoustic wave drivers does not exceed 1 millimeter.

[0127] For example, the vibration frequency of the bulk acoustic wave driver 12 is 2.4 GHz, the vibration region of the bulk acoustic wave driver 12 is a pentagon, and the area of the pentagon is 1100 um 2 . The distance between two adjacent bulk acoustic wave drivers 12 can be 1 millimeter, and the liquid layer is, for example, conventional ink, and the thickness of the liquid layer is, for example, 150 micrometers.

[0128] In some embodiments, as Figure 2As shown, optionally, dielectric layers 22 and 23 may be provided between dielectric layer 21 and acoustic reflection layer 121 to isolate signals between dielectric layer 21 and acoustic reflection layer 121. Dielectric layer 24 may also be provided on acoustic reflection layer 121. The materials of dielectric layers 22, 23, and 24 may be insulating materials, materials with low dielectric constants, or oxides such as silicon dioxide, etc.

[0129] In addition, such as Figure 2 As shown, an integrated circuit may also include: a drain or source region 31 located in the substrate 11; a gate dielectric layer 32 located between the substrate 11 and the gate electrode 33, the gate dielectric layer 32 serving as an insulating layer and generally being an insulating material; and a gate electrode 33 located on the upper side of the substrate 11, which is generally being a conductive material.

[0130] In addition, such as Figure 2 As shown, the integrated circuit may also include, for example, an IC device 34 located on the substrate 11. The IC device 34 may be an active device or a passive device, or may include both active and passive devices. Active devices may be, for example, transistors, and passive electronic devices may be, for example, resistors, capacitors, inductors, etc. Alternatively, the IC device 34 may be other electronic devices, which may be a combination of multiple devices or a single device. For example, the IC device 34 may be a field-effect transistor, which includes a pair of source / drain regions 31 disposed in the semiconductor substrate 11, and a gate electrode 33 disposed on the semiconductor substrate 11. Figure 2 For simplicity, only one IC device is labeled, but this application is not limited to this.

[0131] In addition, such as Figure 2 As shown, an integrated circuit may further include: conductive contacts 36 located in the dielectric layer 21; conductive vias 37 located in the dielectric layer 21; and conductive lines 38 located in the dielectric layer 21, the material of which is generally a conductive material. The material of the dielectric layer 21 is generally an insulating material, a low dielectric constant material, or an oxide such as silicon dioxide, etc., but this application is not limited thereto.

[0132] The structure of the embodiments of this application has been described above, but this application is not limited thereto. Specific details of each device or component can be found in related technologies; furthermore, additional [devices / components] may be added. Figures 1 to 3 Devices or components not shown, or reduced Figures 1 to 3 One or more devices or components in it.

[0133] The following describes the method of using the acoustic droplet ejection device according to the embodiments of this application.

[0134] This application also provides an integrated circuit-controlled acoustic droplet ejection method, which uses the aforementioned acoustic droplet ejection device. Figure 4This is a schematic diagram of an acoustic droplet ejection method according to an embodiment of this application, as shown below. Figure 4 As shown, the method includes:

[0135] Step 401: Apply a pulse signal to the first and second electrodes of the acoustic droplet ejection device via the integrated circuit of the dielectric layer of the acoustic droplet ejection device; and

[0136] Step 402: Eject droplets from the liquid layer of the acoustic droplet ejection device;

[0137] 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.

[0138] 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.

[0139] By forming a vibration region through at least partial overlap of the first electrode, piezoelectric layer, and second electrode in a direction perpendicular to the substrate, bulk acoustic waves propagate in the vertical direction and are reflected by the acoustic reflection layer. Upon contact with the liquid layer, high-frequency acoustic waves couple into the liquid layer to generate volume forces, thereby concentrating the energy during liquid ejection and requiring lower ejection power. Furthermore, the droplet diameter can be precisely controlled, the droplet ejection velocity is vertically upward, and the flux of ejected droplets is high.

[0140] 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.

[0141] Therefore, droplet ejection can be driven by the volume force generated by attenuation in a liquid environment.

[0142] In some embodiments, the duration of the volume force is altered by changing the duration of the pulse signal applied to the first and second electrodes, thereby controlling the diameter of the droplets ejected from the liquid layer.

[0143] Therefore, the droplet diameter can be further precisely controlled.

[0144] In some embodiments, the volume force is altered by changing the power of the pulse signal applied to the first electrode and the second electrode, thereby controlling the ejection velocity of the droplets ejected from the liquid layer.

[0145] Therefore, the ejection velocity of the ejected droplets can be further precisely controlled.

[0146] In some embodiments, the duration of the pulse signal is from 1 microsecond to 10 milliseconds; the period of the pulse signal is more than 10 microseconds; and the period of the pulse signal is more than twice the duration.

[0147] Therefore, by applying a high-frequency pulse signal, the piezoelectric layer can generate high-frequency mechanical vibrations due to the inverse piezoelectric effect, thereby generating high-frequency sound waves.

[0148] 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 4 The records.

[0149] The manufacturing method of the integrated circuit-controlled acoustic droplet ejection device according to the embodiments of this application will be described below.

[0150] Figure 5 This is a schematic diagram of a method for manufacturing an acoustic droplet ejection device according to an embodiment of this application, as shown below. Figure 5 As shown, the method includes:

[0151] Step 501: Form an integrated circuit, the integrated circuit being located on a substrate;

[0152] Step 502, forming a bulk acoustic wave actuator, the bulk acoustic wave actuator being located on the upper side of the substrate and having a vibration region.

[0153] Step 502 of forming the bulk acoustic wave driver includes:

[0154] Step 5021: Form an acoustic reflection layer on the upper side of the substrate;

[0155] Step 5022: A first electrode is formed on the upper side of the acoustic reflection layer, and the first electrode is connected to the first conductive part of the integrated circuit through a first interface portion;

[0156] Step 5023: Form a piezoelectric layer on the upper side of the first electrode; and

[0157] Step 5024: A second electrode is formed on the upper side of the piezoelectric layer, and the second electrode is connected to the second conductive part of the integrated circuit through a second interface portion; 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.

[0158] Therefore, bulk acoustic wave actuators can be fabricated using microelectromechanical systems (MEMS) technology and easily integrated with complementary metal-oxide-semiconductor (CMOS) technology. The arrayed actuators offer flexible control methods and are small in size. For example, a single actuator can be controlled by an integrated circuit, or multiple actuators can be controlled by an integrated circuit. Integration with CMOS circuits also reduces signal parasitics and wire interference effects in the circuit structure.

[0159] In some embodiments, the method further includes:

[0160] Step 503, forming a liquid layer, the liquid layer being at least partially located above the vibration region of the bulk acoustic wave driver.

[0161] In some embodiments, the method further includes forming a passivation layer on the upper side of the second electrode.

[0162] In some embodiments, one or more of the bulk acoustic wave drivers are formed on the substrate.

[0163] In some embodiments, a plurality of bulk acoustic wave drivers are located on the upper side of the substrate, and a predetermined distance is spaced between two adjacent bulk acoustic wave drivers.

[0164] The following is another example Figure 2 Taking the integrated circuit-controlled acoustic droplet ejection device 10 as an example, the steps are illustrated by way of example.

[0165] Figure 6 This is an example diagram illustrating the fabrication of an acoustic reflective layer according to an embodiment of this application. (See diagram below.) Figure 6 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.

[0166] 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.

[0167] Figure 7 This is an example diagram of the manufacturing of the first electrode according to an embodiment of this application; Figure 8 This is another example diagram of the manufacturing of the first electrode according to an embodiment of this application; Figure 9 This is an example diagram of the fabrication of a piezoelectric layer according to an embodiment of this application; Figure 10 This is an example diagram of the manufacturing of a dielectric layer according to an embodiment of this application; Figure 11 This is an example diagram of the manufacturing of the second electrode according to an embodiment of this application; Figure 12 This is another example diagram illustrating the fabrication of the second electrode according to an embodiment of this application. (See diagram below.) Figures 7 to 12 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.

[0168] like Figure 7 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 8 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 8 As shown, the first electrode 122 is connected to the first conductive part 211 of the integrated circuit through the first interface part 1221.

[0169] like Figure 9 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 10 As 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.

[0170] like Figure 11 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 12 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 12 As shown, the second electrode 124 is connected to the second conductive part 212 of the integrated circuit through the second interface part 1241.

[0171] Figure 13 This is an example diagram illustrating the fabrication of a passivation layer according to an embodiment of this application. For example... Figure 13As 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.

[0172] The liquid cavity 16 can then be fabricated and the liquid layer 14 formed. For example, the liquid cavity 16 can be fabricated using standard molding processes or laser cutting, and then fixed to the substrate 11. The area of ​​the liquid layer 14 must at least partially cover the vibration region 13 of the bulk acoustic wave actuator. The liquid layer 14 may also extend beyond the vibration region 13. Other non-cavity methods can also be used to limit the position of the liquid layer 14, for example, by making the surface of the region where the bulk acoustic wave actuator 12 overlaps with the liquid layer 14 a hydrophilic surface, and the surface of the region where the bulk acoustic wave actuator 12 does not overlap with the liquid layer 14 a hydrophobic surface.

[0173] Figures 6 to 13 The manufacturing process of the acoustic droplet ejection device 10 is illustrated by way of example, but this application is not limited thereto.

[0174] 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.

[0175] In this embodiment, all manufacturing processes of the bulk acoustic wave actuator, including substrate fabrication, 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 Both the size of the actuator itself and the diameter of the generated droplets are much smaller than those of surface acoustic waves, ultrasonic waves and other acoustic wave devices, so more actuators can be arrayed per unit area.

[0176] Since the circuitry is directly integrated near the driver, the negative impact of circuit parasitics and wire effects on the jetting effect is minimized; each volume acoustic wave driver can be controlled by an integrated circuit, which can effectively control the operation of one or more volume acoustic wave drivers.

[0177] Furthermore, the sound waves from a 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. A smaller pulse signal width allows for smaller droplet diameters, enabling precise control over droplet diameter by adjusting the pulse signal width. With pulse signal periods typically exceeding 10 µs, throughput can reach thousands or even tens of thousands of droplets per second, offering a significant advantage in throughput.

[0178] The embodiments of this application can operate with and without nozzles. In the nozzle-equipped structure, due to the low overall power consumption and heat generation, there is no need to worry about nozzle clogging. The acoustic droplet ejection device of this application embodiment can be applied to inkjet printing, 3D biomanufacturing, etc.

[0179] 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.

[0180] 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.

[0181] 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.

[0182] 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 controlled by an integrated circuit, characterized in that, The device includes: A substrate and a dielectric layer located on the upper side of the substrate; An integrated circuit includes transistor devices disposed in or on the substrate, interconnect structures, and first and second conductive portions disposed in the dielectric layer; and A bulk acoustic wave actuator, located on the upper side of the substrate and having a vibration region; 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 reflection layer, and the first electrode is connected to the first conductive part of the integrated circuit through a first interface portion penetrating the acoustic reflection layer; A piezoelectric layer, at least partially located above the first electrode; The second electrode is located above the piezoelectric layer and is connected to the second conductive portion of the integrated circuit through a second interface portion penetrating the acoustic reflection 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.

2. The apparatus according to claim 1, characterized in that, The device further includes: A liquid layer, at least partially located above the vibration region of the bulk acoustic wave actuator.

3. The apparatus according to claim 1, characterized in that, The device further includes: A passivation layer is located on the upper side of the second electrode.

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

5. The apparatus according to claim 1, characterized in that, The area of ​​the vibration region of the bulk acoustic wave actuator is between 10 square micrometers and 20,000 square micrometers.

6. The apparatus according to claim 2, characterized in that, The thickness of the liquid layer is 1 micrometer to 1 millimeter.

7. The apparatus according to claim 1, characterized in that, The vibration frequency of the bulk acoustic wave driver is from 0.1 GHz to 5 GHz.

8. The apparatus according to claim 1, characterized in that, The distance between the substrate and the bulk acoustic wave driver does not exceed 2 mm.

9. The apparatus according to claim 1, characterized in that, The substrate includes one or more of the bulk acoustic wave drivers, wherein at least one bulk acoustic wave driver is controlled by the integrated circuit to perform droplet ejection.

10. The apparatus according to claim 9, 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.

11. The apparatus according to claim 9, characterized in that, The distance between two independently controlled bulk acoustic wave actuators does not exceed 100 micrometers.

12. The apparatus according to claim 2 or 6, characterized in that, When a pulse signal is applied to the first electrode and the second electrode via the integrated circuit, the piezoelectric layer vibrates in the vibration region and forms a sound wave. At least a portion of the sound wave is reflected by the acoustic reflection layer and transmitted to the liquid layer. The sound wave couples into the liquid layer to generate a volume force, causing the liquid layer to eject droplets.

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

14. An integrated circuit-controlled acoustic droplet ejection method, characterized in that, The method uses the acoustic droplet ejection device as described in any one of claims 1 to 11, 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 via an integrated circuit in the device; and Droplets are ejected from the liquid layer of the acoustic droplet ejection device, the liquid layer being at least partially located above the vibration region of the bulk acoustic wave actuator; 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.

15. The method according to claim 14, 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.

16. A method for manufacturing an acoustic droplet ejection device controlled by an integrated circuit, characterized in that, The method includes: To form an integrated circuit, the integrated circuit including transistor devices and interconnect structures formed in or on a substrate, and a first conductive portion and a second conductive portion formed in a dielectric layer located on the upper side of the substrate; and A bulk acoustic wave actuator is formed, the bulk acoustic wave actuator being located on the upper side of the dielectric layer and having a vibration region; The forming bulk acoustic wave driver includes: An acoustic reflection layer is formed on the upper side of the dielectric layer; A first electrode is formed on the upper side of the acoustic reflection layer, and the first electrode is connected to the first conductive part of the integrated circuit through a first interface portion penetrating the acoustic reflection 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, and the second electrode is connected to the second conductive part of the integrated circuit through a second interface portion penetrating the acoustic reflection 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.

17. The method according to claim 16, characterized in that, The method further includes: A liquid layer is formed, which is at least partially located above the vibration region of the bulk acoustic wave driver.

18. The method according to claim 16, characterized in that, The method further includes: A passivation layer is formed on the upper side of the second electrode.

19. The method according to claim 16, characterized in that, One or more of the bulk acoustic wave drivers are formed on the substrate.

20. The method according to claim 19, 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.

21. An electrical product, characterized in that, The electrical product has an acoustic droplet ejection device controlled by an integrated circuit as described in any one of claims 1 to 13.

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