A MEMS microfluidic device and a manufacturing method thereof

Abstract

The present invention belongs to the technical field of microfluidic devices, and in particular, relates to a MEMS microfluidic device and a manufacturing method thereof. The manufacturing method comprises the following steps: providing a substrate, manufacturing an acoustic wave reflection layer on the substrate; manufacturing a piezoelectric layer structure on the acoustic wave reflection layer; manufacturing a first photoresist layer on the piezoelectric layer structure, and manufacturing a cavity wall on the surface of the first photoresist layer; manufacturing a second photoresist layer on the surface of the cavity wall, processing a first through hole on the second photoresist layer, manufacturing a nozzle on the cavity wall through the first through hole, removing the first photoresist layer and the second photoresist layer, forming a cavity after the first photoresist layer is removed, and the nozzle is connected to the cavity to manufacture a MEMS microfluidic device. The manufacturing method adopts semiconductor technology to manufacture MEMS microfluidic devices, and the substrate can use a large-sized silicon wafer, which is conducive to large-scale production and reduces costs.

Description

Technical Field

[0001] The present invention belongs to the technical field of microfluidic devices, and in particular relates to a MEMS microfluidic device and a manufacturing method thereof. Background Art

[0002] Microfluidic technology and devices are widely used, for example, in the oil and gas industry to study the behavior of crude oil and brine through porous media and in microgravity inspections on the International Space Station. Currently, microfluidic technology and devices are being used more and more widely in the fields of biology and medicine, from drug research to drug delivery, from antibody research to antigen detection, from organ chips to life detection, from gene sequencing to gene delivery, from single cell lysis to 3D printing of artificial organs, and so on.

[0003] Microfluidic systems work by using microelectromechanical (MEMS) devices. Different types of pumps precisely move liquids within the device at speeds ranging from 1 μL / min to 10,000 μL / min. Inside the device, there are microfluidic channels that can manipulate the liquids, such as mixing, chemical or physical reactions. The liquids may carry tiny particles, such as cells or nanoparticles. The microfluidic device enables the manipulation of these particles, for example, the capture and collection of cancer cells from normal cells in the blood.

[0004] Microfluidic devices based on MEMS technology can range in length or width from 1 cm (0.5 in) to 10 cm (4 in). Chip thickness ranges from about 0.5 mm (1 / 64 in) to 5 mm (1 / 4 in). Microfluidic devices have hair-thin microchannels inside that are connected to the outside through holes in the chip called inlet / outlet ports. MEMS devices are piezoelectric or made of thermoplastics such as quartz, piezoelectric ceramics, acrylic, glass, or PDMS. 3D printing can be used to produce microfluidic chips, although it has severe limitations in minimum feature size, surface roughness, optical transparency, or material selection.

[0005] Existing microfluidic devices are based on traditional MEMS technology, which has disadvantages such as poor process stability, reliability, consistency, high manufacturing cost, large size and weight. Summary of the invention

[0006] The object of the present invention is to provide a MEMS microfluidic device and a manufacturing method thereof, aiming to solve the technical problem that the microfluidic device in the prior art is a traditional MEMS process.

[0007] To achieve the above object, an embodiment of the present invention provides a method for manufacturing a MEMS microfluidic device, comprising the following steps:

[0008] Providing a substrate, and manufacturing a sound wave reflecting layer on the substrate;

[0009] Fabricating a piezoelectric layer structure on the sound wave reflecting layer;

[0010] Forming a first photoresist layer on the piezoelectric layer structure, and forming a cavity wall on the surface of the first photoresist layer;

[0011] A second photoresist layer is made on the surface of the cavity wall, a first through hole is processed on the second photoresist layer, a nozzle is made on the cavity wall through the first through hole, the first photoresist layer and the second photoresist layer are removed, a cavity is formed after the first photoresist layer is removed, the nozzle is connected to the cavity, and the MEMS microfluidic device is manufactured.

[0012] Optionally, the step of manufacturing a piezoelectric layer structure on the sound wave reflecting layer includes:

[0013] The lower electrode is made on the sound wave reflecting layer, the piezoelectric material layer is made on the lower electrode, the upper electrode is made on the piezoelectric material layer, a second through hole is made on the piezoelectric material layer, the first conductive layer is led out from the second through hole, the first conductive layer is electrically connected to the lower electrode, the second conductive layer is made along the epitaxial direction of the upper electrode, and the second conductive layer is electrically connected to the upper electrode.

[0014] Optionally, the manufacturing process of the lower electrode and / or the upper electrode is selected from any one of a metal evaporation process, a sputtering process, an atomic layer deposition process, a CVD process, a metal stripping process or a metal etching process; the manufacturing process of the first conductive layer and / or the second conductive layer is selected from any one of a CVD process, a PVD process, a sputtering process, an evaporation process or an electroplating process; and the manufacturing of the second through hole on the piezoelectric material layer includes the following steps: a photolithography process, etching the piezoelectric material layer and removing the photoresist.

[0015] Optionally, the manufacturing method of the MEMS microfluidic device also includes the following steps: a third through hole and a fourth through hole are manufactured above the first conductive layer and the second conductive layer; the third through hole and the fourth through hole are manufactured by photolithography and through hole etching in sequence; the third through hole and the fourth through hole respectively penetrate the cavity wall to the surface of the first conductive layer and the second conductive layer, and metal layers are respectively manufactured in the third through hole and the fourth through hole to obtain a first pad and a second pad.

[0016] Optionally, a passivation layer is covered on the surface of the piezoelectric layer structure, and the first photoresist layer is formed on the passivation layer.

[0017] Optionally, a protective layer is covered on the surface of the cavity wall, and the protective layer is hollowed out at a position corresponding to the nozzle.

[0018] Optionally, producing the nozzle on the cavity wall comprises the following steps: producing the first through hole on the second photoresist layer by a photolithography process, and etching the nozzle on the cavity wall through the first through hole; forming the cavity comprises the following steps: producing the first photoresist layer on the piezoelectric layer structure by a photolithography process, producing a thin film on the first photoresist layer to form the cavity wall, and removing the first photoresist layer through the nozzle to form the cavity in the cavity wall.

[0019] Optionally, the acoustic wave reflecting layer is a Bragg reflector, which is made by alternately stacking a first material layer and a second material layer with different acoustic wave impedances; in the step of manufacturing the acoustic wave reflecting layer on the substrate, the first material layer is a silicon dioxide layer, and the manufacturing process of the silicon dioxide layer is selected from any one of a CVD process, a SACVD process, a PECVD process, a LPCVD process or an ALD process; the second material layer is a tungsten layer, and the manufacturing process of the tungsten layer is selected from any one of a CVD process, a evaporation process, a sputtering process or an ALD process.

[0020] The above one or more technical solutions in the method for manufacturing a MEMS microfluidic device provided in an embodiment of the present invention have at least one of the following technical effects: 1) MEMS microfluidic devices are manufactured using semiconductor technology, and a large-size silicon wafer can be used as the substrate, which is conducive to large-scale production and reduces costs; 2) CMOS-compatible process technology can be used to further improve the yield and reduce manufacturing costs; 3) Multifunctional integrated devices with other devices can be manufactured to improve performance and integration.

[0021] To achieve the above-mentioned purpose, an embodiment of the present invention provides a MEMS microfluidic device, including a substrate, an acoustic wave reflecting layer, a piezoelectric layer structure, a cavity and a nozzle, wherein the acoustic wave reflecting layer is arranged on the substrate; the piezoelectric layer structure is arranged on the acoustic wave reflecting layer; the cavity has a cavity wall, and the cavity wall is arranged on the piezoelectric layer structure and encloses the cavity with the piezoelectric layer structure; the nozzle is arranged on the cavity wall and connected to the cavity.

[0022] Optionally, the MEMS microfluidic device also includes a passivation layer, a protective layer, a first pad and a second pad, the piezoelectric layer structure includes a lower electrode, a piezoelectric material layer, an upper electrode, a first conductive layer and a second conductive layer, the lower electrode is arranged on the acoustic wave reflecting layer, the piezoelectric material layer is arranged on the lower electrode, the upper electrode is arranged on the piezoelectric material layer, the first conductive layer and the second conductive layer are electrically connected to the lower electrode and the upper electrode respectively; the passivation layer covers the surface of the piezoelectric layer structure, the cavity is formed between the cavity wall and the passivation layer, the protective layer covers the surface of the cavity wall, the first pad and the second pad pass through the protective layer, the cavity wall and the passivation layer and are electrically connected to the first conductive layer and the second conductive layer respectively.

[0023] The above one or more technical solutions in the MEMS microfluidic device provided by the embodiment of the present invention have at least one of the following technical effects: the MEMS microfluidic device can be manufactured by semiconductor process, thereby improving process stability, reliability and consistency, and has the characteristics of low manufacturing cost, small size and light weight. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0025] Figure 1 A schematic diagram of manufacturing a sound wave reflecting layer provided in an embodiment of the present invention.

[0026] Figure 2 A schematic diagram of manufacturing a lower electrode provided in an embodiment of the present invention.

[0027] Figure 3 A schematic diagram of manufacturing a piezoelectric material layer provided in an embodiment of the present invention.

[0028] Figure 4 A schematic diagram of manufacturing an upper electrode provided in an embodiment of the present invention.

[0029] Figure 5 A schematic diagram of manufacturing a second through hole provided in an embodiment of the present invention.

[0030] Figure 6 A schematic diagram of manufacturing the first conductive layer and the second conductive layer provided in an embodiment of the present invention.

[0031] Figure 7 A schematic diagram of manufacturing a passivation layer provided in an embodiment of the present invention.

[0032] Figure 8 A schematic diagram of manufacturing a first photoresist layer provided in an embodiment of the present invention.

[0033] Fig. 9 A schematic diagram of the manufacture of a cavity wall provided in an embodiment of the present invention.

[0034] Fig.10 A schematic diagram of manufacturing a second photoresist layer provided in an embodiment of the present invention.

[0035] Fig.11 A schematic diagram of the manufacture of the nozzle and the cavity provided in an embodiment of the present invention.

[0036] Fig.12 A schematic diagram of manufacturing a protective layer provided in an embodiment of the present invention.

[0037] Fig.13 A schematic diagram of manufacturing a first soldering pad and a second soldering pad provided in an embodiment of the present invention.

[0038] Fig.14 A schematic diagram of the operation of a MEMS microfluidic device provided in an embodiment of the present invention.

[0039] Description of reference numerals:

[0040] 1. Substrate; 2. Sound wave reflecting layer; 21. First material layer; 22. Second material layer; 3. Piezoelectric layer structure; 31. Lower electrode; 32. Piezoelectric material layer; 321. Second through hole; 33. Upper electrode; 34. First conductive layer; 35. Second conductive layer; 4. First photoresist layer; 5. Cavity wall; 51. Cavity; 52. Nozzle; 6. Second photoresist layer; 61. First through hole; 7. Passivation layer; 8. Protective layer; 9a. First pad; 9b. Second pad; 10. External power supply. DETAILED DESCRIPTION

[0041] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the embodiments of the present invention, and should not be construed as limiting the present invention.

[0042] In the description of the embodiments of the present invention, it should be understood that if there are directional indications in the embodiments of the present invention, such as up, down, left, right, front, back, inside, outside, etc., the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings. It is only for the convenience of describing the embodiments of the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be understood as a limitation on the present invention.

[0043] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0044] In the embodiments of the present invention, unless otherwise clearly specified and limited, if there are terms such as "installed", "connected", "connected", "fixed", etc., they should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0045] In an embodiment of the present invention, a method for manufacturing a MEMS microfluidic device is provided, comprising the following steps:

[0046] Providing a substrate 1, and manufacturing a sound wave reflecting layer 2 on the substrate 1;

[0047] A piezoelectric layer structure 3 is fabricated on the sound wave reflecting layer 2;

[0048] Forming a first photoresist layer 4 on the piezoelectric layer structure 3, and forming a cavity wall 5 on the surface of the first photoresist layer 4;

[0049] A second photoresist layer 6 is made on the surface of the cavity wall 5, and a first through hole 61 is processed on the second photoresist layer 6. A nozzle 52 is made on the cavity wall 5 through the first through hole 61. The first photoresist layer 4 and the second photoresist layer 6 are removed. After the first photoresist layer 4 is removed, a cavity 51 is formed. The nozzle 52 is connected to the cavity 51, and a MEMS microfluidic device is manufactured.

[0050] In an embodiment of the present invention, Figure 1 As shown, the provided substrate 1 can be silicon, sapphire, glass, etc., and the size is preferably 3-12 inches (75mm-300mm).

[0051] Specifically, the MEMS microfluidic device is made on a wafer, and the substrate material of the wafer can be any of the aforementioned: silicon, sapphire, glass, etc., with a thickness of 100um-1000um. For silicon substrates, the wafer size is more preferably 4-12 inches (100-300mm). The wafer after manufacturing is in a grid shape, and each grid is a chip. The chip can be square or rectangular, and the side length ranges from 200um-5mm. The number of devices (MEMS microfluidic devices) on each chip ranges from dozens to hundreds or even tens of thousands. The present invention adopts semiconductor technology to manufacture the MEMS microfluidic device, which improves the integration, reliability, consistency, and uniformity of the chip, simplifies the manufacturing process, reduces costs, and is conducive to large-scale production and application.

[0052] In an embodiment of the present invention, Figure 1 As shown, the specific method of making the acoustic wave reflecting layer 2 on the substrate 1 is as follows: the acoustic wave reflecting layer 2 in the present invention is a Bragg reflector, which is composed of two materials with different acoustic impedances. The function of the Bragg reflector is to reflect the sound waves into the piezoelectric layer.

[0053] Specifically, the Bragg reflector is made by alternately stacking a first material layer 21 and a second material layer 22 with different acoustic wave impedances. Moreover, the thickness of each layer is λ / 4 of the acoustic wave, so that most of the waves will be reflected back and superimposed with the original waves, thereby reducing energy loss.

[0054] Exemplarily, the Bragg reflector is preferably composed of low-impedance silicon dioxide and high-impedance tungsten alternately stacked. The thickness of each layer is 1 / 4 wavelength, and the number of layers can be 2-50. The method for making the material layer can be different according to different materials. In the present invention, silicon dioxide can be made by CVD, SACVD, PECVD, LPCVD, ALD and other methods. Tungsten can be made by CVD, evaporation, sputtering, ALD and other methods.

[0055] Specifically, Figure 2-Figure 6 As shown, the step of making a piezoelectric layer structure on the sound wave reflecting layer includes: making a lower electrode 31 on the sound wave reflecting layer 2, making a piezoelectric material layer 32 on the lower electrode 31, making an upper electrode 33 on the piezoelectric material layer 32, making a second through hole 321 on the piezoelectric material layer 32, leading out a first conductive layer 34 from the second through hole 321, the first conductive layer 34 is electrically connected to the lower electrode 31, and a second conductive layer 35 is made along the epitaxial direction of the upper electrode 33, and the second conductive layer 35 is electrically connected to the upper electrode 33.

[0056] In an embodiment of the present invention, Figure 2As shown, the lower electrode 31 is made on the acoustic wave reflection layer 2 as follows: the electrode material is preferably Mo, Au, Ti, Al, W, Pt, Cu, Ta, etc. The thickness of the lower electrode 31 is between 0.1-2um. There are many ways to make the lower electrode 31, such as metal evaporation, sputtering, atomic layer deposition, CVD, etc.

[0057] Specifically, the manufacturing process of the lower electrode 31 is generally the following two:

[0058] 1) Metal lift-off process, the production steps are as follows: a) photolithography, including coating, alignment, exposure, and development; b) metal deposition; c) metal lift-off; d) photoresist removal; e) wafer cleaning.

[0059] 2) Metal Etch process (Metal Etch), the production steps are as follows: a) wafer surface treatment; b) metal deposition; c) photolithography, including coating, alignment, exposure, and development; d) metal etching, including dry etching or wet etching; e) photoresist removal; f) wafer cleaning.

[0060] In an embodiment of the present invention, Figure 3 As shown, the steps of making the piezoelectric material layer 32 on the lower electrode 31 are as follows: the piezoelectric material is preferably AlN, GaN, PZT, ZnO, lithium tantalate and lithium niobate, etc., and can be single crystal or polycrystalline, doped or non-doped. The thickness of the piezoelectric material layer 32 is between 10nm and 5um.

[0061] In an embodiment of the present invention, Figure 4 As shown, the steps of making the upper electrode 33 on the piezoelectric material layer 32 are as follows: the electrode material is preferably Mo, Au, Ti, Al, W, Pt, Cu, Ta, etc. The thickness of the upper electrode 33 is between 0.1-2um. There are many ways to make the upper electrode 33, such as metal evaporation, sputtering, atomic layer deposition, CVD, etc.

[0062] Specifically, the manufacturing process of the upper electrode 33 includes the following two processes:

[0063] 1) Metal lift-off process, the production steps are as follows: a) photolithography, including coating, alignment, exposure, and development; b) metal deposition; c) metal lift-off; d) photoresist removal; e) wafer cleaning.

[0064] 2) Metal Etch process (Metal Etch), the production steps are as follows: a) wafer surface treatment; b) metal deposition; c) photolithography, including coating, alignment, exposure, and development; d) metal etching, including dry etching or wet etching; e) photoresist removal; f) wafer cleaning.

[0065] In the embodiment of the present invention, in order to lead out the lower electrode 31, it is necessary to etch a via through the piezoelectric material layer 32, such as Figure 5 As shown, the steps of making the second through hole 321 on the piezoelectric material layer 32 are specifically as follows:

[0066] a) Photolithography, including coating, alignment, exposure and development;

[0067] b) etching the piezoelectric material layer 32. Different etching methods are used for different materials. For example, if aluminum nitride is used as the piezoelectric material, dry etching, i.e., plasma etching, can be used. The gas used can be a mixed gas of Cl2 and BCl3;

[0068] c) photoresist removal, which can be dry or wet;

[0069] d) Wafer cleaning.

[0070] In an embodiment of the present invention, Figure 6 As shown, the first conductive layer 34 and the second conductive layer 35 are made as follows: the first conductive layer 34 and the second conductive layer 35 are preferably made of metals such as Al, W, Cu, Au, etc., and can be made by CVD, PVD, sputtering, evaporation, electroplating and other methods.

[0071] In an embodiment of the present invention, Figure 7 As shown, in order to protect the resonator (the combination of the acoustic wave reflection layer 2 and the piezoelectric layer structure 3), the passivation layer 7 is covered on the surface of the piezoelectric layer structure 3. The steps of making the passivation layer 7 on the piezoelectric layer structure 3 are as follows: the material of the passivation layer 7 is selected from any one of silicon oxide, silicon nitride, silicon carbide or aluminum nitride, and can also be a stack of more than one material. The commonly used methods for making the passivation layer 7 include PECVD, SACVD, LPCVD, MOCVD, PVD and ALD. The thickness of the passivation layer 7 is preferably 10nm-2um.

[0072] In an embodiment of the present invention, Figure 8-Figure 11 As shown, the steps of forming the cavity 51 include:

[0073] a) a photolithography process, including coating, alignment, exposure, and development, to form a first photoresist layer 4; the first photoresist layer 4 defines the size, shape, and other features of the cavity 51;

[0074] b) forming a thin film on the first photoresist layer 4 to form a cavity wall 5, and the thin film can be a metal, a nitride, an oxide, etc.;

[0075] In an embodiment of the present invention, Fig.10 and Fig.11 As shown, the steps of making the nozzle 52 on the cavity wall 5 are as follows:

[0076] a) a photolithography process, including coating, alignment, exposure, and development, to form a second photoresist layer 6, and to process a first through hole 61 on the second photoresist layer 6; and to make a nozzle 52 on the cavity wall 5 through the first through hole 61;

[0077] b) the nozzle 52 performs etching, degumming and cleaning to remove the first photoresist layer 4 and the second photoresist layer 6, and a cavity 51 is formed after the first photoresist layer 4 is removed;

[0078] c) removing the first photoresist layer 4 through the nozzle 52 to form a cavity 51 in the cavity wall 5 .

[0079] Preferably, the diameter of the nozzle 52 is between 1-100 um.

[0080] In an embodiment of the present invention, the preparation method further comprises the following steps: covering the surface of the cavity wall 5 with a protective layer 8. Fig.12 As shown, the protective layer 8 is made as follows: the material of the protective layer 8 is preferably nitride, oxide, benzocyclobutene and polyimide film, and its thickness is preferably 10-100nm. The protective layer 8 is hollowed out at the position corresponding to the nozzle 52 so that the nozzle 52 is exposed.

[0081] In an embodiment of the present invention, Fig.13 As shown, in order to lead out the upper electrode 33 and the lower electrode 31, the preparation method further includes the following steps: making a first pad 9a and a second pad 9b. The steps of making the first pad 9a and the second pad 9b include:

[0082] a) Photolithography, including coating, alignment, exposure and development;

[0083] b) through-hole etching, the third through-hole and the fourth through-hole respectively pass through the protective layer 8, the cavity wall 5, and the passivation layer 7, until they stop on the surface of the first conductive layer 34 and the second conductive layer 35; the etching is preferably performed by a dry process;

[0084] c) Making a metal layer. Making a metal layer in the third through hole and the fourth through hole respectively to obtain a first pad 9a and a second pad 9b. The material for making the pad is preferably Au, Al, Cu, etc., and can be made by evaporation, sputtering, or electroplating.

[0085] In summary, the manufacturing method of the present invention adopts semiconductor technology to manufacture MEMS microfluidic devices, and the substrate 1 can use a large-sized silicon wafer, which is conducive to large-scale production and reduces costs. The manufacturing method can adopt CMOS-compatible process technology to further improve the yield and reduce manufacturing costs. The manufacturing method can manufacture multifunctional integrated devices with other devices to improve performance and integration.

[0086] The MEMS microfluidic device manufactured according to the above manufacturing method includes a substrate 1, an acoustic wave reflecting layer 2, a piezoelectric layer structure 3, a cavity 51 and a nozzle 52, wherein the acoustic wave reflecting layer 2 is arranged on the substrate 1. The piezoelectric layer structure 3 is arranged on the acoustic wave reflecting layer 2. The cavity 51 has a cavity wall 5, which is arranged on the piezoelectric layer structure 3 and encloses the cavity 51 with the piezoelectric layer structure 3. The nozzle 52 is arranged on the cavity wall 5 and connected to the cavity 51.

[0087] Specifically, the MEMS microfluidic device further includes a passivation layer 7, a protective layer 8, a first pad 9a and a second pad 9b, and the piezoelectric layer structure 3 includes a lower electrode 31, a piezoelectric material layer 32, an upper electrode 33, a first conductive layer 34 and a second conductive layer 35. The lower electrode 31 is arranged on the acoustic wave reflection layer 2, the piezoelectric material layer 32 is arranged on the lower electrode 31, the upper electrode 33 is arranged on the piezoelectric material layer 32, and the first conductive layer 34 and the second conductive layer 35 are respectively electrically connected to the lower electrode 31 and the upper electrode 33. The passivation layer 7 covers the surface of the piezoelectric layer structure 3, the cavity 51 is formed between the cavity wall 5 and the passivation layer 7, the protective layer 8 covers the surface of the cavity wall 5, and the first pad 9a and the second pad 9b both pass through the protective layer 8, the cavity wall 5 and the passivation layer 7, and are respectively electrically connected to the first conductive layer 34 and the second conductive layer 35.

[0088] In the application of the device, the cavity 51 is used to store liquid. Fig.14 As shown, when the microfluidic device is connected to an external power supply 10 through the first pad 9a and the second pad 9b to apply voltage to the device, the piezoelectric effect of the piezoelectric material converts electrical energy into mechanical energy, causing the resonator to vibrate up and down. The vibration of the resonator ejects the liquid in the cavity 51 through the nozzle 52. The size of the droplet is determined by the nozzle 52, and the frequency of the ejection is controlled by the power frequency. By changing the size of the nozzle 52 and the frequency of the power supply, different liquid volumes and ejection frequencies can be obtained, realizing various microfluidic and microfluidic applications.

[0089] The MEMS microfluidic device can be manufactured by semiconductor technology, thereby improving process stability, reliability and consistency, and has the characteristics of low manufacturing cost, small size and light weight.

[0090] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for manufacturing a MEMS microfluidic device, characterized in that: The following steps are involved: Providing a substrate, and manufacturing a sound wave reflecting layer on the substrate; Fabricating a piezoelectric layer structure on the sound wave reflecting layer; Forming a first photoresist layer on the piezoelectric layer structure, and forming a cavity wall on the surface of the first photoresist layer; A second photoresist layer is formed on the surface of the cavity wall, a first through hole is formed on the second photoresist layer, a nozzle is formed on the cavity wall through the first through hole, the first photoresist layer and the second photoresist layer are removed, a cavity is formed after the first photoresist layer is removed, the nozzle is connected to the cavity, and the MEMS microfluidic device is manufactured; Forming the cavity comprises the following steps: forming the first photoresist layer on the piezoelectric layer structure by a photolithography process, forming a thin film on the first photoresist layer to form the cavity wall, wherein the thin film is a metal, a nitride, or an oxide, and removing the first photoresist layer by the nozzle to form the cavity in the cavity wall; A lower electrode is made on the sound wave reflecting layer, a piezoelectric material layer is made on the lower electrode, an upper electrode is made on the piezoelectric material layer, a second through hole is made on the piezoelectric material layer, a first conductive layer is led out from the second through hole, the first conductive layer is electrically connected to the lower electrode, a second conductive layer is made along the epitaxial direction of the upper electrode, and the second conductive layer is electrically connected to the upper electrode.

2. The method for manufacturing a MEMS microfluidic device according to claim 1, characterized in that: The manufacturing process of the lower electrode and / or the upper electrode is selected from any one of a metal evaporation process, a sputtering process, an atomic layer deposition process, a CVD process, a metal stripping process or a metal etching process; the manufacturing process of the first conductive layer and / or the second conductive layer is selected from any one of a CVD process, a PVD process, a sputtering process, an evaporation process or an electroplating process; and the manufacturing of the second through hole on the piezoelectric material layer includes the following steps: a photolithography process, etching the piezoelectric material layer and removing the photoresist.

3. The method for manufacturing a MEMS microfluidic device according to claim 2, characterized in that: The following steps are also included: A third through hole and a fourth through hole are made above the first conductive layer and the second conductive layer; the third through hole and the fourth through hole are made by photolithography and through hole etching in sequence; the third through hole and the fourth through hole respectively penetrate the cavity wall to the surface of the first conductive layer and the second conductive layer, and metal layers are respectively made in the third through hole and the fourth through hole to obtain a first pad and a second pad.

4. The method for manufacturing a MEMS microfluidic device according to claim 1, characterized in that: A passivation layer is covered on the surface of the piezoelectric layer structure, and the first photoresist layer is formed on the passivation layer.

5. The method for manufacturing a MEMS microfluidic device according to claim 1, characterized in that: A protective layer is covered on the surface of the cavity wall, and the protective layer is hollowed out at a position corresponding to the nozzle.

6. The method for manufacturing a MEMS microfluidic device according to any one of claims 1 to 5, characterized in that: The step of manufacturing the nozzle on the cavity wall comprises the following steps: manufacturing the first through hole on the second photoresist layer by a photolithography process, and etching the nozzle on the cavity wall through the first through hole.

7. The method for manufacturing a MEMS microfluidic device according to any one of claims 1 to 5, characterized in that: The acoustic wave reflecting layer is a Bragg reflector, which is made by alternately stacking a first material layer and a second material layer with different acoustic wave impedances; in the step of manufacturing the acoustic wave reflecting layer on the substrate, the first material layer is a silicon dioxide layer, and the manufacturing process of the silicon dioxide layer is selected from any one of a CVD process, a SACVD process, a PECVD process, a LPCVD process or an ALD process; The second material layer is a tungsten layer, and a manufacturing process of the tungsten layer is selected from any one of a CVD process, an evaporation process, a sputtering process or an ALD process.

8. A MEMS microfluidic device manufactured by the manufacturing method according to any one of claims 1 to 7, characterized in that: include: substrate; an acoustic wave reflecting layer, the acoustic wave reflecting layer being arranged on the substrate; A piezoelectric layer structure, wherein the piezoelectric layer structure is arranged on the sound wave reflecting layer; A cavity, the cavity having a cavity wall, the cavity wall being arranged on the piezoelectric layer structure and enclosing the cavity with the piezoelectric layer structure; as well as A nozzle is disposed on the cavity wall and connected to the cavity.

9. The MEMS microfluidic device according to claim 8, characterized in that: It also includes a passivation layer, a protective layer, a first pad and a second pad, the piezoelectric layer structure includes a lower electrode, a piezoelectric material layer, an upper electrode, a first conductive layer and a second conductive layer, the lower electrode is arranged on the acoustic wave reflecting layer, the piezoelectric material layer is arranged on the lower electrode, the upper electrode is arranged on the piezoelectric material layer, and the first conductive layer and the second conductive layer are electrically connected to the lower electrode and the upper electrode respectively; The passivation layer covers the surface of the piezoelectric layer structure, the cavity is formed between the cavity wall and the passivation layer, the protective layer covers the surface of the cavity wall, and the first pad and the second pad pass through the protective layer, the cavity wall and the passivation layer and are electrically connected to the first conductive layer and the second conductive layer respectively.

Images