KR102655050B1 - Vertical type bulk acoustic wave micofluidic filtering module having sandwich structure and method of manufacturing the same - Google Patents

Abstract

The present invention discloses a vertical type bulk acoustic wave microfluidic filtering module having a sandwich structure and a method of manufacturing the same.
In particular, the present invention generates waves in the vertical direction using BAW (Bulk Acoustic Wave) instead of the existing SAW (Surface Acoustic Wave), thereby improving the separation efficiency of fine particles by supplying more efficient wave energy within the fluid. , Removal of fine particles by controlling the position where fine particles are concentrated by selectively controlling standing waves or traveling waves through phase control of the vibration of bulk acoustic waves generated from the first and second piezoelectric elements having a vertically symmetrical sandwich structure. Disclosed is a vertical type bulk acoustic wave microfluidic filtering module with a sandwich structure that can maximize efficiency and a method of manufacturing the same.

Description

Vertical type bulk acoustic wave microfluidic filtering module with sandwich structure and method of manufacturing the same {VERTICAL TYPE BULK ACOUSTIC WAVE MICOFLUIDIC FILTERING MODULE HAVING SANDWICH STRUCTURE AND METHOD OF MANUFACTURING THE SAME}

The present invention relates to a vertical type bulk acoustic wave microfluidic filtering module with a sandwich structure and a manufacturing method thereof. More specifically, the present invention relates to a vertical type bulk acoustic wave microfluidic filtering module with a sandwich structure and a method of manufacturing the same. More specifically, the present invention relates to a vertical type bulk acoustic wave microfluidic filtering module with a sandwich structure and a method of manufacturing the same. By supplying more efficient wave energy into the fluid by generating it in the vertical direction, the separation efficiency of fine particles can be improved, while controlling the phase of the vibration of bulk acoustic waves generated from the first and second piezoelectric elements with a vertically symmetrical sandwich structure. About a vertical type bulk acoustic wave microfluidic filtering module with a sandwich structure that can maximize the removal efficiency of fine particles by controlling the position where fine particles are concentrated by selectively controlling standing waves or traveling waves and a method of manufacturing the same. will be.

Surface acoustic waves are acoustic waves that are generated from electrical signals as a result of the piezoelectric effect and propagate along the surface of a piezoelectric substrate. The electric field of surface acoustic waves is concentrated near the surface of a piezoelectric substrate and can interact with the conduction electrons of another semiconductor placed directly on the surface.

In general, a surface acoustic wave filter applies the characteristics of surface acoustic waves transmitted along the surface of a piezoelectric substrate as a frequency selection function element. The surface acoustic wave filter forms an IDT (Inter Digital Transducer), a comb-shaped transducer, with metal electrodes on a piezoelectric substrate. When an electric field is applied, the surface of the substrate is temporarily distorted, and this action is used to generate surface acoustic waves. It enables the movement of fine particles larger than the wavelength of surface acoustic waves.

Related prior literature includes Korean Patent Publication No. 10-2009-0085327 (published on August 7, 2009), which discloses a mixer and filter having a porous spiral structure, and a micro-channel device equipped with the same. .

The purpose of the present invention is to generate waves in the vertical direction using BAW (Bulk Acoustic Wave) instead of the existing SAW (Surface Acoustic Wave) to improve the separation efficiency of fine particles by supplying more efficient wave energy within the fluid. , Removal of fine particles by controlling the position where fine particles are concentrated by selectively controlling standing waves or traveling waves through phase control of the vibration of bulk acoustic waves generated from the first and second piezoelectric elements having a vertically symmetrical sandwich structure. To provide a vertical type bulk acoustic wave microfluidic filtering module with a sandwich structure that can maximize efficiency and a manufacturing method thereof.

A vertical-type bulk acoustic wave microfluidic filtering module having a sandwich structure according to an embodiment of the present invention to achieve the above object includes a first substrate, a first buffer layer formed to cover the upper surface of the first substrate, and the first buffer layer. 1 A first module unit having a first piezoelectric element formed on a buffer layer; A second substrate having a symmetrical structure with the first module unit and bonded to the first substrate, a second buffer layer formed to cover the upper surface of the second substrate, and a second piezoelectric element formed on the second buffer layer. a second module unit having; a bonding member disposed between the first and second module parts to bond the first and second substrates; and a microfluidic channel formed to penetrate a portion of the first and second substrates located in a space between the first and second module parts, respectively, for passing a fluid containing fine particles. do.

Each of the first and second substrates is preferably one of a Si substrate, Al ₂ O ₃ substrate, SiC substrate, and GaAs substrate.

The first piezoelectric element includes a first lower electrode, a first piezoelectric layer formed on the first lower electrode, and a first upper electrode formed on the first piezoelectric layer, and the second piezoelectric element includes a second piezoelectric element. It includes a lower electrode, a second piezoelectric layer formed on the second lower electrode, and a second upper electrode formed on the second piezoelectric layer.

The first and second upper electrodes and the first and second lower electrodes each include gold (Au), silver (Ag), copper (Cu), nickel (Ni), titanium (Ti), aluminum (Al), and chromium ( It is made of one or more materials selected from Cr), tungsten (W), and tin (Sn).

Each of the first and second piezoelectric layers includes at least one selected from a PZT-based piezoelectric material, a BNT-based piezoelectric material, and a PVDF-based piezoelectric material.

The first buffer layer is formed of a material having a value between the acoustic impedance of the first piezoelectric layer and the acoustic impedance of the fluid, and the second buffer layer has a value between the acoustic impedance of the second piezoelectric layer and the acoustic impedance of the fluid. It is formed from a substance that has

Each of the first and second buffer layers is formed of one or more materials selected from SiO ₂ , AlN, InAlN, and InN.

Each of the first and second piezoelectric elements has a thickness of 1㎛ to 10mm.

The bonding member physically bonds the first and second substrates together using a wafer bonding method.

The bulk acoustic wave microfluidic filtering module selectively controls standing waves or traveling waves by controlling the phase of bulk acoustic waves generated from the first and second piezoelectric elements arranged in a mutually symmetrical structure.

The bulk acoustic wave microfluidic filtering module generates standing waves from the first and second piezoelectric elements through phase control of vibration using the first and second piezoelectric elements, respectively, and concentrates fine particles in the center of the microfluidic channel. Selectively removes fine particles.

The bulk acoustic wave microfluidic filtering module generates traveling waves from the first and second piezoelectric elements through phase control of vibration using the first and second piezoelectric elements, respectively, to filter out fine particles on the upper or lower side of the microfluidic channel. It focuses and selectively removes fine particles.

To achieve the above object, a method of manufacturing a vertical-type bulk acoustic wave microfluidic filtering module with a sandwich structure according to an embodiment of the present invention includes the steps of (a) forming a first buffer layer covering the upper surface of a first substrate; (b) forming a first piezoelectric element on the first buffer layer; (c) selectively etching a portion of the lower surface of the first substrate to form a first through hole, thereby forming a first module unit having the first substrate, a first buffer layer, a first piezoelectric element, and a first through hole. ; (d) a second substrate having a symmetrical structure with the first module portion at a lower portion spaced apart from the first module portion and having a second through hole facing the first substrate, and covering a lower surface of the second substrate. disposing a second module unit having a second buffer layer formed so as to form a second buffer layer and a second piezoelectric element formed on the second buffer layer; and (e) disposing a bonding member between the first and second module parts, and then bonding the first and second module parts using a wafer bonding method using a bonding member.

The first and second buffer layers are formed of one or more materials selected from SiO ₂ , AlN, InAlN, and InN.

Each of the first and second piezoelectric elements has a thickness of 1㎛ to 10mm.

In step (c), the etching is anisotropically etching the lower surface of the first substrate using micromachining technology to form a first through hole penetrating from the lower surface to the upper surface of the first substrate.

In step (e), the first and second module parts are bonded to each other via the bonding member, so that the first and second module parts of the first and second substrates located in the space between the first and second module parts And the second through hole is combined to form a microfluidic channel for passing a fluid containing fine particles therein.

The vertical type bulk acoustic wave microfluidic filtering module with a sandwich structure according to the present invention and its manufacturing method generate waves in the vertical direction using BAW (Bulk Acoustic Wave) instead of the existing SAW (Surface Acoustic Wave) to filter the fluid. By supplying more efficient wave energy, the separation efficiency of fine particles can be improved, and by controlling the phase of the vibration of bulk acoustic waves generated from the first and second piezoelectric elements with a vertically symmetrical sandwich structure, it is possible to separate standing waves or traveling waves. By selectively controlling the location where fine particles are concentrated, it is possible to maximize the removal efficiency of fine particles.

In addition, the vertical type bulk acoustic wave microfluidic filtering module with a sandwich structure according to the present invention and its manufacturing method apply voltage to the first and second piezoelectric elements arranged in a symmetrical sandwich structure at a position corresponding to the microfluidic channel. When applied, up and down vibration is generated through volumetric vibration in the thickness mode by the first and second piezoelectric elements with a thickness of 1㎛ ~ 10mm, and higher frequency driving is possible compared to SAW, enabling separation of even smaller particles. .

Therefore, the vertical-type bulk acoustic wave microfluidic filtering module with a sandwich structure according to the present invention and its manufacturing method are compared to the existing fine particle separation method using SAW, which separates particles on a horizontal plane, in the vertical direction with the help of gravity. Separation of fine particles occurs and re-diffusion of fine particles is reduced.

As a result, the vertical type bulk acoustic wave microfluidic filtering module with a sandwich structure according to the present invention and its manufacturing method are acoustic waves generated by vertical vibration through volume vibration in the thickness mode by the first and second piezoelectric elements. By spreading evenly throughout the fluid as a medium, the separation efficiency of fine particles can be maximized and the removal efficiency of fine particles within the fluid can be improved.

Figure 1 is a perspective view showing a typical SAW micro filtering module.
Figure 2 is a plan view and cross-sectional view showing a typical SAW micro filtering module.
Figures 3 and 4 are cross-sectional views for explaining the operating principle of a general SAW micro filtering module.
Figures 5 and 6 are schematic diagrams showing a general SAW micro filtering module in more detail.
Figure 7 is a schematic diagram to explain the operating principle of a general SAW micro filtering module.
Figure 8 is a cross-sectional view showing a vertical type bulk acoustic wave microfluidic filtering module having a sandwich structure according to an embodiment of the present invention.
FIG. 9 is an enlarged cross-sectional view showing the joint portion of the first and second substrates of FIG. 8.
10 and 11 are schematic diagrams illustrating the operating principle of a vertical-type bulk acoustic wave microfluidic filtering module with a sandwich structure according to an embodiment of the present invention.
12 to 16 are cross-sectional process views showing a method of manufacturing a vertical-type bulk acoustic wave microfluidic filtering module with a sandwich structure according to an embodiment of the present invention.

The advantages and features of the present invention and methods for achieving them will become clear by referring to the embodiments described in detail below along with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and will be implemented in various different forms. The present embodiments only serve to ensure that the disclosure of the present invention is complete and that common knowledge in the technical field to which the present invention pertains is provided. It is provided to fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

Hereinafter, with reference to the attached drawings, a vertical type bulk acoustic wave microfluidic filtering module having a sandwich structure and a manufacturing method thereof according to a preferred embodiment of the present invention will be described in detail as follows.

This will be described in more detail with reference to the attached drawings below.

Figure 1 is a perspective view showing a general SAW micro-filtering module, and Figure 2 is a plan view and cross-sectional view showing a general SAW micro-filtering module.

As shown in Figures 1 and 2, a general SAW micro filtering module 100 includes a first IDT electrode 122 and a second IDT electrode 124 spaced apart in a comb pattern on a piezoelectric substrate 110. ) is disposed, and through this, surface acoustic waves (SAW, Surface Acoustic Wave) are generated to separate fine particles in the fluid. In addition, the general SAW micro-filtering module 100 may further include an absorber 130 disposed at one edge of the substrate 110.

At this time, the wavelength (λ = 1/f) of the surface acoustic wave is determined by the gap between the first IDT electrode 122 and the second IDT electrode 124, and the movement of fine particles larger than the corresponding wavelength of the surface acoustic wave is possible. Let's do it.

Figures 3 and 4 are cross-sectional views to explain the operating principle of a general SAW micro filtering module.

As shown in Figures 3 and 4, the general SAW micro-filtering module 100 uses a substrate 110 with piezoelectricity to generate surface acoustic waves, and an IDT electrode unit 120 having a wavelength smaller than the size of fine particles. ) is placed single or in plural to generate a traveling wave or standing wave to move the fine particles (P) in a specific direction or to collect the fine particles (P) at the node to remove the fine particles contained in the fluid. Particles (P) are removed.

However, in the general SAW micro filtering module 100, surface acoustic waves generated from the IDT electrode unit 120 on the piezoelectric substrate 110 propagate to one or both sides of the IDT electrode unit 120, and thus proceed to the opposite side of the flow path. There was a problem that surface acoustic waves were not utilized and were lost.

Figures 5 and 6 are schematic diagrams showing a general SAW micro filtering module in more detail.

As shown in FIGS. 5 and 6, a general SAW micro filtering module 100 includes a first IDT 122 electrode and a second IDT electrode 124 spaced apart in a comb pattern on a piezoelectric substrate 110. ) is placed around the microfluidic channel 140 having a flow path 144 for passing a fluid containing fine particles (P), and through this, surface acoustic waves (SAW) are generated. Wave) is generated to separate fine particles (P) in the fluid.

Here, the microfluidic channel 140 has a fluid injection port 142 for injecting a fluid containing fine particles (P), and a fluid injection port 142 for moving the fluid containing the fine particles (P) injected through the fluid injection port 142. It may include a flow path 144, a fluid outlet 146 for discharging the fluid passing through the flow path 144, and a fine particle outlet 148 for collecting fine particles (P) in the fluid.

As such, the general SAW micro-filtering module 100 uses a substrate 110 having piezoelectricity to generate surface acoustic waves, and includes a single or plural IDT electrode unit 120 having a wavelength smaller than the size of the fine particles (P). A method is used to generate a traveling wave or a standing wave to move the fine particles (P) in a specific direction or to collect the fine particles (P) at the fine particle discharge port 148.

The wavelength (λ = 1/f) of SAW is determined by the gap between the first IDT electrode 122 and the second IDT electrode 124 of the IDT electrode unit 120, and the SAW generated in the IDT electrode unit 120 It enables the movement of fine particles (P) of a size larger than the wavelength.

Figure 7 is a schematic diagram to explain the operating principle of a general SAW micro filtering module.

As shown in FIG. 7, a typical SAW micro-filtering module 100 has a microfluidic channel 140 disposed in the central portion of a piezoelectric substrate 110, and an IDT at a position spaced apart from the microfluidic channel 140. It may have a structure in which the electrode unit 120 is disposed.

Here, the surface acoustic waves generated from the IDT electrode unit 120 on the piezoelectric substrate 110 are transmitted into the microfluidic channel 140, and the elastic waves decrease according to the x-axis travel distance.

In addition, some wave energy such as leaky surface acoustic waves (Leaky SAW) is transmitted to the y-axis in the upper direction of the microfluidic channel 140, but the total energy decreases rapidly and most of the energy is transmitted to the surface of the piezoelectric substrate 110. Energy is concentrated.

Therefore, there is a problem that the efficiency of separating fine particles in the fluid passing through the inside of the microfluidic channel 140 is inevitably lowered in the vertical direction.

To solve this problem, the vertical-type bulk acoustic wave microfluidic filtering module with a sandwich structure according to an embodiment of the present invention uses BAW (Bulk Acoustic Wave) instead of the existing SAW (Surface Acoustic Wave) to transmit waves in the vertical direction. It is possible to improve the separation efficiency of fine particles by supplying more efficient wave energy within the fluid, and to selectively use standing or traveling waves by controlling the phase of the signal applied to the upper and lower piezoelectric elements with a vertically symmetrical sandwich structure. Controlled.

As a result, the vertical-type bulk acoustic wave microfluidic filtering module with a sandwich structure according to an embodiment of the present invention separates particles in the vertical direction with the help of gravity, compared to the existing fine particle separation method using SAW, which separates particles on a horizontal plane. Not only is the re-diffusion of fine particles low due to separation of fine particles, but it is also possible to control the location where fine particles are concentrated by selectively controlling standing waves or traveling waves, thereby maximizing the removal efficiency of fine particles.

This will be described in more detail with reference to the attached drawings below.

FIG. 8 is a cross-sectional view showing a vertical type bulk acoustic wave microfluidic filtering module having a sandwich structure according to an embodiment of the present invention, and FIG. 9 is an enlarged cross-sectional view showing the joint portion of the first and second substrates of FIG. 8. am.

Referring to Figures 8 and 9, the vertical type bulk acoustic wave microfluidic filtering module 200 having a sandwich structure according to an embodiment of the present invention includes a first module part 235, a second module part 265, It includes a bonding member 270 and a microfluidic channel 280.

The first module unit 235 includes a first substrate 210, a first buffer layer 220 formed to cover the upper surface of the first substrate 210, and a first piezoelectric element formed on the first buffer layer 220 ( 230).

The first substrate 210 may have a plate shape with an upper surface and a lower surface opposite to the upper surface, but it is not limited to this plate shape, and its shape can be changed in various ways.

The first substrate 210 may be any one of a Si substrate, Al ₂ O ₃ substrate, SiC substrate, and GaAs substrate, and it is more preferable to use a Si substrate.

The first buffer layer 220 is formed to cover the top surface of the first substrate 210.

This first buffer layer 220 serves as a support plate for separation from fluid and vibration, and at the same time serves to transmit maximum energy through acoustic impedance matching.

Table 1 shows a comparison of acoustic impedance measurement values for each material of the first buffer layer, first piezoelectric element, and medium.

[Table 1]

As shown in Table 1, acoustic impedance measurement values for each material of the first buffer layer 220, the first piezoelectric element 230, and the fluid as a medium are shown.

Here, Z _A is acoustic impedance, ρ is density, and c means volume velocity.

At this time, the first buffer layer 220 serves as a support plate for separation from fluid and vibration, and at the same time serves to transmit maximum energy through acoustic impedance matching.

For this purpose, the first buffer layer 220 is preferably formed of a material having a value between the acoustic impedance of the first piezoelectric layer 234 and the acoustic impedance of the fluid. This first buffer layer 220 may be composed of a single layer or multiple layers for efficient acoustic impedance matching. More specifically, the first buffer layer 220 is preferably formed of one or more materials selected from SiO ₂ , AlN, InAlN, and InN.

The first piezoelectric element 230 is formed on the first buffer layer 220.

This first piezoelectric element 230 includes a first lower electrode 232, a first piezoelectric layer 234 formed on the first lower electrode 232, and a first upper electrode formed on the first piezoelectric layer 234. Includes electrode 236.

Here, the first upper electrode 236 and the first lower electrode 232 each include gold (Au), silver (Ag), copper (Cu), nickel (Ni), titanium (Ti), aluminum (Al), and chromium. It is formed of one or more materials selected from (Cr), tungsten (W), and tin (Sn).

The first piezoelectric layer 234 includes one or more types selected from PZT-based piezoelectric materials, BNT-based piezoelectric materials, and PVDF-based piezoelectric materials. Here, the first piezoelectric layer 234 is BaTiO ₃ , BiTiO ₃ , PbTiO ₃ , Pb[Zr _x Ti _1-x ]O ₃ , KNbO ₃ , LiNbO ₃ , LiTaO ₃ , Na ₂ WO ₃ , NaNbO ₃ , NaTiO ₃ and ZnO, etc. are more preferable.

This first piezoelectric element 230 may have a thickness of 1 μm to 10 mm. In this way, the first piezoelectric element 230, which has a thickness of 1㎛ ~ 10mm, generates up and down vibration through thickness longitudinal mode (TLM), and is capable of driving at a higher frequency than SAW, producing smaller particles. It is possible to separate up to

The second module portion 265 has a symmetrical structure with the first module portion 235. To this end, the second module unit 265 has substantially the same configuration as the first module unit 235.

The second module unit 265 includes a second substrate 240 bonded to the first substrate 210, a second buffer layer 250 formed to cover the upper surface of the second substrate 240, and a second buffer layer 250. ) has a second piezoelectric element 260 formed on it. Here, it is preferable that the lower surface of the first substrate 210 of the first module unit 235 and the lower surface of the second substrate 240 of the second module unit 265 are bonded to each other.

Like the first substrate 210, the second substrate 240 may be any one of a Si substrate, an Al ₂ O ₃ substrate, a SiC substrate, and a GaAs substrate, and it is more preferable to use a Si substrate.

Like the first buffer layer 220, the second buffer layer 250 is preferably formed of a material having a value between the acoustic impedance of the second piezoelectric layer 264 and the acoustic impedance of the fluid. This second buffer layer 250 may be composed of a single layer or multiple layers for efficient acoustic impedance matching. More specifically, the second buffer layer 250 is preferably formed of one or more materials selected from SiO ₂ , AlN, InAlN, and InN.

The second piezoelectric element 260 is formed on the second buffer layer 250.

This second piezoelectric element 260 includes a second lower electrode 262, a second piezoelectric layer 264 formed on the second lower electrode 262, and a second upper electrode formed on the second piezoelectric layer 264. Includes electrode 266.

Here, the second upper electrode 266 and the second lower electrode 262 each include gold (Au), silver (Ag), copper (Cu), nickel (Ni), titanium (Ti), aluminum (Al), and chromium. It is formed of one or more materials selected from (Cr), tungsten (W), and tin (Sn).

The second piezoelectric layer 264 includes one or more types selected from PZT-based piezoelectric materials, BNT-based piezoelectric materials, and PVDF-based piezoelectric materials. Here, the second piezoelectric layer 264 is BaTiO ₃ , BiTiO ₃ , PbTiO ₃ , Pb[Zr _x Ti _1-x ]O ₃ , KNbO ₃ , LiNbO ₃ , LiTaO ₃ , Na ₂ WO ₃ , NaNbO ₃ , NaTiO ₃ and ZnO, etc. are more preferable.

This second piezoelectric element 260 may have a thickness of 1 μm to 10 mm. In this way, the second piezoelectric element 260, which has a thickness of 1㎛ ~ 10mm, generates vertical vibration through thickness longitudinal mode (TLM), and is capable of driving at a higher frequency than SAW, producing smaller particles. It is possible to separate up to

The bonding member 270 is disposed between the first and second module parts 235 and 265 to bond the first and second substrates 210 and 240.

This bonding member 270 physically bonds the first and second substrates 210 and 240 between the first and second substrates 210 and 240 using a wafer bonding method. Accordingly, the first and second substrates 210 and 240 are physically bonded to each other by the bonding member 270.

The microfluidic channel 280 is formed to penetrate a portion of the first and second substrates 210 and 240 located in the space between the first and second module parts 235 and 265, respectively, and contains fine particles. Formed to pass fluid. At this time, the microfluidic channel 280 may be formed to penetrate the central portion and edge portion of the first and second substrates 210 and 240, respectively.

Here, each of the first and second piezoelectric elements 230 and 260 is preferably disposed at a position corresponding to the microfluidic channel 280 in order to supply uniform wave energy to the microfluidic channel 280.

In particular, in the present invention, the first and second piezoelectric elements 230 and 260 are respectively disposed in a vertical direction on the first and second buffer layers 220 and 250 spaced apart from the microfluidic channel 280 at regular intervals. In this way, the first and second piezoelectric elements 230 and 260 are respectively installed in the vertical direction with respect to the microfluidic channel 280, thereby separating the fine particles in the vertical direction with the help of gravity. Redistribution can be reduced.

These microfluidic channels 280 are anisotropically etched on the lower surfaces of the first and second substrates 210 and 240 using micromachining technology, thereby penetrating from the lower surfaces to the upper surfaces of the first and second substrates 210 and 240, respectively. can be formed. At this time, the microfluidic channel 250 is sealed by the first buffer layer 220 covering the top surface of the first substrate 210 and the second buffer layer 250 covering the top surface of the second substrate 240.

Therefore, the vertical-type bulk acoustic wave microfluidic filtering module 200 with a sandwich structure according to an embodiment of the present invention has a vertical separation method assisted by gravity, compared to the existing fine particle separation method using SAW, which separates particles on a horizontal plane. Since fine particles are separated in one direction and have the advantage of low re-diffusion of fine particles, the separation efficiency of fine particles can be improved by supplying more efficient wave energy into the fluid.

In addition, the vertical type bulk acoustic wave microfluidic filtering module 200 having a sandwich structure according to an embodiment of the present invention has a vertically symmetrical sandwich structure to absorb bulk sound generated from the first and second piezoelectric elements 230 and 260. By selectively controlling standing waves or traveling waves through wave phase control, it is possible to control the location where fine particles are concentrated, thereby maximizing the removal efficiency of fine particles.

Meanwhile, FIGS. 10 and 11 are schematic diagrams for explaining the operating principle of a vertical-type bulk acoustic wave microfluidic filtering module with a sandwich structure according to an embodiment of the present invention, and will be described in conjunction with FIG. 8.

First, as shown in FIGS. 8 and 10, the vertical type bulk acoustic wave microfluidic filtering module 200 having a sandwich structure according to an embodiment of the present invention includes a first substrate 210 and a first buffer layer 220. ) and a first module unit 235 having a first piezoelectric element 230, has a symmetrical structure with the first module unit 235, and includes a second substrate 240, a second buffer layer 250, and a second piezoelectric A bonding member 270 for bonding the first and second substrates 210 and 240 between the second module portion 265 having the element 260 and the first and second module portions 235 and 265, It is formed to penetrate a portion of the first and second substrates 210 and 240, respectively, and includes a microfluidic channel 280 for passing a fluid containing fine particles.

At this time, the vertical type bulk acoustic wave microfluidic filtering module 200 having a sandwich structure according to an embodiment of the present invention provides the first and second vibration phase control using the first and second piezoelectric elements 230 and 260. Standing waves are generated from the second piezoelectric elements 230 and 260, respectively, to concentrate fine particles in the center of the microfluidic channel 280 and selectively remove the fine particles.

In addition, as shown in FIGS. 8 and 11, the vertical type bulk acoustic wave microfluidic filtering module 200 having a sandwich structure according to an embodiment of the present invention includes first and second piezoelectric elements 230 and 260. Through phase control of vibration using , traveling waves are generated from the first and second piezoelectric elements 230 and 260, respectively, and the fine particles are concentrated on the upper or lower side of the microfluidic channel 280 to selectively remove the fine particles. .

In this way, the vertical type bulk acoustic wave microfluidic filtering module 200 having a sandwich structure according to an embodiment of the present invention generates a vertically symmetrical sandwich structure when driving the first and second piezoelectric elements 230 and 260. By selectively controlling standing waves or traveling waves through phase control of bulk acoustic waves, it is possible to control the location where fine particles are concentrated, thereby maximizing the removal efficiency of fine particles.

Hereinafter, with reference to the attached drawings, a method of manufacturing a vertical type bulk acoustic wave microfluidic filtering module having a sandwich structure according to an embodiment of the present invention will be described.

12 to 16 are cross-sectional process views showing a method of manufacturing a vertical-type bulk acoustic wave microfluidic filtering module with a sandwich structure according to an embodiment of the present invention.

As shown in FIG. 12, a first buffer layer 220 is formed to cover the top surface of the first substrate 210.

Here, the first substrate 210 may have a plate shape with an upper surface and a lower surface opposite to the upper surface, but it is not limited to this plate shape, and its shape can be changed in various ways.

The first substrate 210 may be any one of a Si substrate, Al ₂ O ₃ substrate, SiC substrate, and GaAs substrate, and it is more preferable to use a Si substrate.

The first buffer layer 220 serves as a support plate for separation from fluid and vibration, and at the same time transmits maximum energy through acoustic impedance matching. For this purpose, the first buffer layer 220 is preferably formed of a material having a value between the acoustic impedance of the first piezoelectric layer and the acoustic impedance of the fluid. This first buffer layer 220 may be composed of a single layer or multiple layers for efficient acoustic impedance matching. More specifically, the first buffer layer 220 is preferably formed of one or more materials selected from SiO ₂ , AlN, InAlN, and InN.

As shown in FIG. 13, the first piezoelectric element 230 is formed on the first buffer layer 220.

Here, the first piezoelectric element 230 includes a process of forming a first lower electrode material layer on the first buffer layer 220, a process of forming a first piezoelectric material layer on the first lower electrode material layer, and a first piezoelectric material layer. 1. A process of forming a first upper electrode material layer on a piezoelectric material layer and selectively patterning the first lower electrode material layer, the first piezoelectric material layer, and the first upper electrode material layer to form a first lower electrode 232; It may include forming a first piezoelectric element 230 including a first piezoelectric layer 234 and a first upper electrode 236.

In this process, the first upper electrode material layer, the first lower electrode material layer, and the first piezoelectric material layer are formed using sputtering, E-beam vacuum deposition, and molecular beam epitaxy. ) and metal organic chemical vapor deposition (Metal Organic Chemical Vapor Deposition), respectively, but is not limited thereto.

At this time, the first upper electrode 236 and the first lower electrode 232 each include gold (Au), silver (Ag), copper (Cu), nickel (Ni), titanium (Ti), aluminum (Al), and chromium. It is formed of one or more materials selected from (Cr), tungsten (W), and tin (Sn).

The first piezoelectric layer 234 includes one or more types selected from PZT-based piezoelectric materials, BNT-based piezoelectric materials, and PVDF-based piezoelectric materials. _Here , _{the first} piezoelectric _{layer is} BaTiO ₃ , BiTiO ₃ , _{PbTiO 3 , Pb [ Zr} It is more preferable to select

This first piezoelectric element 230 may have a thickness of 1 μm to 10 mm. In this way, the first piezoelectric element 230, which has a thickness of 1㎛ ~ 10mm, generates up and down vibration through thickness longitudinal mode (TLM), and is capable of driving at a higher frequency than SAW, producing smaller particles. It is possible to separate up to

As shown in FIG. 14, a first through hole H1 is formed by selectively etching a portion of the lower surface of the first substrate 210, thereby forming the first substrate 210, the first buffer layer 220, and the first piezoelectric A first module portion 235 having an element 230 and a first through hole H1 is formed.

In this step, the etching is anisotropically etching the lower surface of the first substrate 210 using micro machining technology to form a first through hole H1 penetrating from the lower surface to the upper surface of the first substrate 210. Accordingly, the first through hole H1 may have a tapered cross-sectional structure in which the width decreases from the lower surface to the upper surface of the first substrate 210 . At this time, the first through hole H1 may be formed to penetrate the central portion and the edge portion of the first substrate 210, respectively.

As shown in FIG. 15, at the lower part spaced apart from the first module part 235, a second through hole H2 is formed, which has a symmetrical structure with the first module part 235 and faces the first substrate 210. A second module having a second substrate 240, a second buffer layer 250 formed to cover the upper surface of the second substrate 240, and a second piezoelectric element 260 formed on the second buffer layer 250. Place part 265.

Here, it is preferable to arrange the lower surface of the first substrate 210 of the first module unit 235 and the lower surface of the second substrate 240 of the second module unit 265 to face each other.

Like the first substrate 210, the second substrate 240 may be any one of a Si substrate, an Al ₂ O ₃ substrate, a SiC substrate, and a GaAs substrate, and it is more preferable to use a Si substrate.

The second buffer layer 250 serves as a support plate for separation from fluid and vibration, and at the same time transmits maximum energy through acoustic impedance matching. To this end, the second buffer layer 250 is preferably formed of a material having a value between the acoustic impedance of the second piezoelectric layer 264 and the acoustic impedance of the fluid. This second buffer layer 250 may be composed of a single layer or multiple layers for efficient acoustic impedance matching. More specifically, the second buffer layer 250 is preferably formed of one or more materials selected from SiO ₂ , AlN, InAlN, and InN.

This second piezoelectric element 260 may have a thickness of 1 μm to 10 mm. In this way, the second piezoelectric element 260, which has a thickness of 1㎛ ~ 10mm, generates vertical vibration through thickness longitudinal mode (TLM), and is capable of driving at a higher frequency than SAW, producing smaller particles. It is possible to separate up to

Next, as shown in FIGS. 15 and 16, after placing the bonding member 270 between the first and second module parts 235 and 265, the first and second module parts 235 and 265 are bonded using a wafer bonding method using the bonding member 270.

Here, it is preferable to bond using a wafer bonding method using the bonding member 260. Accordingly, the first and second substrates 210 and 240 are bonded by a wafer bonding method using the bonding member 260 located between the first and second substrates 210 and 240. Accordingly, the first and second substrates 210 and 240 are physically bonded to each other by the bonding member 260.

In this step, the first and second module parts 235 and 265 are bonded to each other via the bonding member 270, thereby forming a second module located in the space between the first and second module parts 235 and 265. The first and second through holes H1 and H2 of the first and second substrates 210 and 240 are combined to form a microfluidic channel 280 for passing a fluid containing fine particles therein.

At this time, the first and second piezoelectric elements 230 and 260 are preferably disposed at positions corresponding to the microfluidic channel 280 in order to evenly supply wave energy to the microfluidic channel 280. In the present invention, the first and second piezoelectric elements 230 and 260 are arranged in a symmetrical structure in the vertical direction on the first and second buffer layers 220 and 250, respectively, spaced apart from the microfluidic channel 280 at regular intervals. do. In this way, the first and second piezoelectric elements 230 and 260 are installed in a symmetrical structure in the vertical direction with respect to the microfluidic channel 280, thereby separating fine particles in the vertical direction with the help of gravity. Re-diffusion of particles can be reduced.

As a result, the present invention generates waves in the vertical direction using BAW (Bulk Acoustic Wave) instead of the existing SAW (Surface Acoustic Wave), thereby improving the separation efficiency of fine particles by supplying more efficient wave energy within the fluid. A position where fine particles are concentrated by selectively controlling a standing wave or a traveling wave through phase control of the vibration of the bulk acoustic wave generated from the first and second piezoelectric elements 230 and 260 having a vertically symmetrical sandwich structure. Through control, the removal efficiency of fine particles can be maximized.

With this, the method for manufacturing a vertical type bulk acoustic wave microfluidic filtering module with a sandwich structure according to an embodiment of the present invention can be completed.

As seen so far, the method of manufacturing a vertical type bulk acoustic wave microfluidic filtering module with a sandwich structure according to an embodiment of the present invention uses BAW (Bulk Acoustic Wave) instead of the existing SAW (Surface Acoustic Wave) to generate the wave. The separation efficiency of fine particles can be improved by supplying more efficient wave energy in the fluid by generating in the vertical direction, and the phase of the vibration of the bulk acoustic wave generated from the first and second piezoelectric elements having a vertically symmetrical sandwich structure. By selectively controlling standing waves or traveling waves, it is possible to maximize the removal efficiency of fine particles by controlling the location where fine particles are concentrated.

In addition, the method of manufacturing a vertical type bulk acoustic wave microfluidic filtering module with a sandwich structure according to an embodiment of the present invention includes first and second piezoelectric elements disposed in a symmetrical sandwich structure at a position corresponding to the microfluidic channel. When voltage is applied, up and down vibration is generated through volumetric vibration in the thickness mode by the first and second piezoelectric elements with a thickness of 1㎛ ~ 10mm, and higher frequency driving is possible compared to SAW, enabling separation of even smaller particles. do.

Therefore, the method of manufacturing a vertical-type bulk acoustic wave microfluidic filtering module with a sandwich structure according to an embodiment of the present invention is a method of manufacturing fine particles in the vertical direction with the help of gravity, compared to the existing fine particle separation method using SAW, which separates particles on a horizontal plane. As a result, separation of fine particles occurs and re-diffusion of fine particles is reduced.

As a result, the method of manufacturing a vertical-type bulk acoustic wave microfluidic filtering module with a sandwich structure according to an embodiment of the present invention produces sound generated by vertical vibration through volumetric vibration in the thickness mode by the first and second piezoelectric elements. As the wave propagates evenly throughout the fluid medium, the separation efficiency of fine particles can be maximized and the removal efficiency of fine particles within the fluid can be improved.

Although the above description focuses on the embodiments of the present invention, various changes or modifications can be made at the level of a person skilled in the art in the technical field to which the present invention pertains. These changes and modifications can be said to belong to the present invention as long as they do not depart from the scope of the technical idea provided by the present invention. Therefore, the scope of rights of the present invention should be determined by the claims described below.

200: Bulk acoustic wave microfluidic filtering module
210: first substrate
220: first buffer layer
230: first piezoelectric element
232: first lower electrode
234: first piezoelectric layer
236: first upper electrode
235: first module part
240: second substrate
250: second buffer layer
260: second piezoelectric element
262: second lower electrode
264: second piezoelectric layer
266: second upper electrode
265: second module part
270: Bonding member
280: microfluidic channel
P: fine particles

Claims (17)

A first module unit having a first substrate, a first buffer layer formed to cover an upper surface of the first substrate, and a first piezoelectric element formed on the first buffer layer;
A second substrate having a symmetrical structure with the first module unit and bonded to the first substrate, a second buffer layer formed to cover the upper surface of the second substrate, and a second piezoelectric element formed on the second buffer layer. a second module unit having;
a bonding member disposed between the first and second module parts to bond the first and second substrates; and
a microfluidic channel formed to penetrate a portion of the first and second substrates located in a space between the first and second module portions, respectively, for passing a fluid containing fine particles;
A vertical type bulk acoustic wave microfluidic filtering module having a sandwich structure, comprising:
According to paragraph 1,
Each of the first and second substrates is
A vertical type bulk acoustic wave microfluidic filtering module having a sandwich structure, characterized in that it is one of a Si substrate, Al ₂ O ₃ substrate, SiC substrate, and GaAs substrate.
According to paragraph 1,
The first piezoelectric element includes a first lower electrode, a first piezoelectric layer formed on the first lower electrode, and a first upper electrode formed on the first piezoelectric layer,
The second piezoelectric element is a vertical device having a sandwich structure, comprising a second lower electrode, a second piezoelectric layer formed on the second lower electrode, and a second upper electrode formed on the second piezoelectric layer. Type bulk acoustic wave microfluidic filtering module.
According to paragraph 3,
Each of the first and second upper electrodes and the first and second lower electrodes is
One or more materials selected from gold (Au), silver (Ag), copper (Cu), nickel (Ni), titanium (Ti), aluminum (Al), chromium (Cr), tungsten (W), and tin (Sn) A vertical type bulk acoustic wave microfluidic filtering module having a sandwich structure, characterized in that it is formed.
According to paragraph 3,
Each of the first and second piezoelectric layers is
A vertical type bulk acoustic wave microfluidic filtering module having a sandwich structure comprising at least one selected from the group consisting of PZT-based piezoelectric material, BNT-based piezoelectric material, and PVDF-based piezoelectric material.
According to paragraph 3,
The first buffer layer is formed of a material having a value between the acoustic impedance of the first piezoelectric layer and the acoustic impedance of the fluid,
The second buffer layer is a vertical type bulk acoustic wave microfluidic filtering module having a sandwich structure, wherein the second buffer layer is formed of a material having a value between the acoustic impedance of the second piezoelectric layer and the acoustic impedance of the fluid.
According to clause 6,
Each of the first and second buffer layers is
A vertical type bulk acoustic wave microfluidic filtering module having a sandwich structure, characterized in that it is formed of one or more materials selected from SiO ₂ , AlN, InAlN and InN.
According to paragraph 1,
Each of the first and second piezoelectric elements is
A vertical type bulk acoustic wave microfluidic filtering module with a sandwich structure having a thickness of 1㎛ ~ 10mm.
According to paragraph 1,
The bonding member is
A vertical type bulk acoustic wave microfluidic filtering module having a sandwich structure, characterized in that the first and second substrates are physically bonded between the first and second substrates using a wafer bonding method.
According to paragraph 1,
The bulk acoustic wave microfluidic filtering module is
Vertical type bulk acoustic wave microfluidic with a sandwich structure, wherein standing waves or traveling waves are selectively controlled by controlling the phase of bulk acoustic waves generated from the first and second piezoelectric elements arranged in a mutually symmetrical structure. Filtering module. According to clause 10,
The bulk acoustic wave microfluidic filtering module is
Through phase control of vibration using the first and second piezoelectric elements, standing waves are generated from the first and second piezoelectric elements, respectively, and the fine particles are concentrated in the center of the microfluidic channel to selectively remove the fine particles. Vertical type bulk acoustic wave microfluidic filtering module with a sandwich structure.
According to clause 10,
The bulk acoustic wave microfluidic filtering module is
Through phase control of vibration using the first and second piezoelectric elements, traveling waves are generated from the first and second piezoelectric elements, respectively, and the fine particles are concentrated on the upper or lower side of the microfluidic channel to selectively remove fine particles. A vertical type bulk acoustic wave microfluidic filtering module having a sandwich structure.
(a) forming a first buffer layer covering the top surface of the first substrate;
(b) forming a first piezoelectric element on the first buffer layer;
(c) selectively etching a portion of the lower surface of the first substrate to form a first through hole, thereby forming a first module unit having the first substrate, a first buffer layer, a first piezoelectric element, and a first through hole. ;
(d) a second substrate having a symmetrical structure with the first module portion at a lower portion spaced apart from the first module portion and having a second through hole facing the first substrate, and covering a lower surface of the second substrate. disposing a second module unit having a second buffer layer formed so as to form a second buffer layer and a second piezoelectric element formed on the second buffer layer; and
(e) disposing a bonding member between the first and second module parts, and then bonding the first and second module parts using a wafer bonding method using a bonding member;
In step (e), the first and second module parts are bonded to each other via the bonding member, so that the first and second module parts of the first and second substrates located in the space between the first and second module parts and a method for manufacturing a vertical type bulk acoustic wave microfluidic filtering module having a sandwich structure, wherein the second through hole is combined to form a microfluidic channel for passing a fluid containing fine particles therein.
According to clause 13,
The first and second buffer layers are
A method of manufacturing a vertical type bulk acoustic wave microfluidic filtering module having a sandwich structure, characterized in that it is formed of one or more materials selected from SiO ₂ , AlN, InAlN and InN.
According to clause 13,
Each of the first and second piezoelectric elements is
A method of manufacturing a vertical type bulk acoustic wave microfluidic filtering module having a sandwich structure, characterized in that it has a thickness of 1㎛ ~ 10mm.
According to clause 13,
In step (c) above,
The etching is
Manufacture of a vertical type bulk acoustic wave microfluidic filtering module with a sandwich structure, characterized in that the lower surface of the first substrate is anisotropically etched using micromachining technology to form a first through hole penetrating from the lower surface to the upper surface of the first substrate. method.
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