CN100549689C - Acoustic wave sensing device with integrated micro-channel, manufacturing method thereof and acoustic wave sensor - Google Patents

Abstract

The invention provides an acoustic wave sensing device with an integrated micro-channel, a manufacturing method thereof and an acoustic wave sensor. The present invention can further integrate the micro flow channel on the same substrate with piezoelectric property by the same processing method or bonding method. The invention utilizes the new element manufacture and design to manufacture the element with good piezoelectric property, stable temperature compensation property and firm structure, so that the plate flexural wave can be applied to the liquid sensor. Therefore, the invention can solve the problems of poor piezoelectric property and film structure of the existing sound wave sensing device.

Description

Acoustic wave sensing device with integrated micro-channel, manufacturing method thereof, and acoustic wave sensor

technical field

The present invention provides an acoustic wave sensing device with an integrated micro-channel and its method, especially a sensor made of a piezoelectric block material as a substrate and processed by micro-electromechanical technology. It can be applied to the analysis of specific components in liquid and gas states.

Background technique

Due to the wave propagation characteristics of the flat plate flexural wave (Flexural Plate Wave, FPW), it has the characteristic of limited energy transfer in the liquid, so it is used in the liquid sensor. Existing FPW components mainly use silicon substrates as a platform to grow piezoelectric thin films and complete the fabrication of components after etching. However, in practical applications, it is difficult to grasp the characteristics of growing multilayer thin films, and the piezoelectric properties of piezoelectric films are important parameters that determine the performance characteristics of FPW devices. In addition, the structure of the film is relatively fragile, and it is easily broken in the application of FPW components.

In U.S. Patent No. 5,212,988, a layer structure is used for the piezoelectric material, so that it can generate symmetrical and asymmetrical Lamb waves; and a ground electrode layer is required in the design of the manufacturing ). In U.S. Patent No. 5,212,988, it is also shown to be fabricated using thin film deposition and silicon etching. In addition, in U.S. Patent No. 6,688,158, emphasis is placed on the use of sacrificial layer micro-maching to complete components with a smaller area, so as to achieve the purpose of arraying, and the piezoelectric layer material is aluminum nitride (aluminum nitride), zinc oxide (zinc oxide) and lead zirconium titanate (lead zirconium titanate), etc.

In the existing literature, Qing-Yun Caiz et al., "Vapor recognition with an integrated array of polymer-coated flexural plate wave sensors" Sensors and Actuators B, Volume 62, pages 121-130, AD 2000. The flat plate flexural wave structure in this article is based on a silicon substrate and a piezoelectric film is used as an actuating structure, but it can be integrated and designed into an array structure and combined with a circuit measurement system; the application is mainly focused on gas above identification.

Philippe Luginbuhl et al., "Microfabricated Lamb Wave Device Based on PZT Sol-Gel Thin Film for Mechanical Transport of SolidParticles and Liquids" Journal of microelectro-mechanical, Volume 73, pp. 112-123, AD 2001. The flat-plate flexural wave structure in this article shows that it uses FPW to cause fluid to transfer solid particles and fluid through mechanical motion, but it does not prove the result of sensing in fluid.

From the above, it can be seen that the above-mentioned existing acoustic wave sensing device obviously has deficiencies and shortcomings in actual use. Therefore, in order to improve the above-mentioned shortcomings, the inventor has devoted himself to research and finally proposed an invention that is reasonably designed and effectively improves the above-mentioned shortcomings.

Contents of the invention

In view of this, the purpose of the present invention is to solve the problems of existing acoustic wave sensing devices such as poor piezoelectric properties, weak film structures or poor stability. In order to achieve the above-mentioned purpose, the present invention provides an acoustic wave sensing device with integrated micro-channel and its method, which utilizes new element manufacturing and design to produce a device with good piezoelectric properties, stable temperature compensation properties and a firm structure. Components that will allow flat plate flexural waves to be applied to liquid state sensors. Therefore, the present invention proposes to use a piezoelectric bulk material as the substrate, make the sensing area into a piezoelectric thin plate by electromechanical or chemical processing, and then use the interdigitated electrode structure (Inter-digital transducer, IDT) to make the plate flex Wave. In the present invention, the microfluidic channel system can be further integrated with the same processing method or bonding method.

The acoustic wave sensing device of the present invention, the acoustic wave sensing device comprises: a substrate with piezoelectric properties, the substrate material can be a quartz, lithium niobate or a tantalum niobate, the substrate is processed by electromechanical grinding or chemical etching The thickness of the substrate in a certain substrate area is smaller than the wavelength of the acoustic wave transmission, and it has the conditions to generate flat plate flexure waves, and the area of the substrate forming a thin plate generates acoustic waves or stress wave transmissions for acoustic sensing of gas or liquid phase molecules;

An electrode layer with interdigitated structure is arranged on the front or back side of the substrate area with conditions for generating plate flexural waves, and the electrode layer with interdigitated structure includes two corresponding first electrode layers and A second electrode layer, and these electrode layers use metal as the structural layer, wherein a sensing material is coated on a transmission path between the first electrode layer and the second electrode layer to form a sensing area;

A material layer with electrode characteristic protection, the material layer is made of high molecular polymer, coated on the periphery of the first electrode layer and the second electrode layer, but the sensing function of the sensing area is not protected by the protection Material layer effects.

In addition, the acoustic wave sensing device may further include a micro-channel, which is formed by electromechanical grinding or chemical etching in the sensing area under the condition of generating plate flexural waves; thereby forming an acoustic wave sensor with an integrated micro-channel measuring device. The present invention can further integrate micro-channels on the same substrate with piezoelectric properties by the same processing method or bonding method to form an acoustic wave sensor with micro-channels including more than two acoustic wave sensing devices of the present invention.

As mentioned above, the manufacturing method of the acoustic wave sensing device of the present invention includes the following steps: firstly, the thickness of the substrate in a certain region on a substrate with piezoelectric characteristics is less than Acoustic waves transmit wavelengths, and make the thinned substrate region have the conditions to generate flat plate flexural waves; then form an electrode layer with a finger-like structure on the substrate region with flat plate flexural wave conditions, wherein the fingered The electrode layer of the forked structure includes two corresponding one first electrode layer and one second electrode layer, what's more, if the previous step adopts the single-side processing method, then the electrode layer with the forked structure is in the The front, back, or both sides of the substrate area under the flat plate flexural wave condition are formed; then a sensing material is coated on a transmission path between the electrode layers with a finger-like structure to form a sensing area , wherein the sensing material can be coated on the same side of the electrode layer with interdigitated structure, the opposite side or both sides at the same time; and coating an electrode protection material on the electrode layer with interdigitated structure around.

The above-mentioned steps may finally include: forming a micro-channel in the sensing area under the condition of generating plate flexure waves by means of electromechanical grinding or chemical etching; thus, forming an acoustic wave sensor with an integrated micro-channel device. Wherein this step can be carried out simultaneously with the initial step of making the substrate thickness of a certain region on the substrate with piezoelectric properties smaller than the wavelength of the acoustic wave transmission.

Description of drawings

FIG. 1A is a top view of an acoustic wave sensing device with an integrated microchannel of the present invention under a single etched side;

FIG. 1B is a perspective view of the acoustic wave sensing device with integrated micro-channel of the present invention under the etching side;

FIG. 1C is a three-dimensional cross-sectional view of an acoustic wave sensing device with an integrated micro-channel of the present invention under a single side of etching;

Fig. 2A is the top view of the acoustic wave sensing device of the present invention under the etched double sides;

FIG. 2B is a perspective view of the acoustic wave sensing device of the present invention under the etched sides;

Fig. 2C is a three-dimensional cross-sectional view of the acoustic wave sensing device of the present invention under the etching bilateral sides;

FIG. 2D is a top view of the acoustic wave sensing device with integrated micro-channels under the etched double sides of the present invention;

2E is a three-dimensional cross-sectional view of the acoustic wave sensing device with integrated micro-channels under the etched sides of the present invention;

3A is a perspective view of the acoustic wave sensing device of the present invention as a reference sensing device under the etched sides;

3B is a three-dimensional cross-sectional view of an acoustic wave sensing device with a sensing layer under etching on both sides of the present invention;

Fig. 4A is the top view of the acoustic wave sensor with integrated micro-channel of the present invention;

FIG. 4B is a perspective view of an acoustic wave sensor with integrated micro-channels of the present invention;

FIG. 4C is a three-dimensional cross-sectional body of the acoustic wave sensor with integrated micro-channel of the present invention;

5 is a flow chart of the manufacturing method of the acoustic wave sensing device of the present invention; and

FIG. 6 is a flow chart of the manufacturing method of the acoustic wave sensing device with integrated micro-channel of the present invention.

Component description

Figure 1A, Figure 1B and Figure 1C:

Acoustic sensing device 10

Substrates with piezoelectric properties 11

Electrode layer with interdigitated structure 12

Area where sensing material is applied 13

Material layer with electrode characteristic protection 14

Microchannel 15

Figure 2A, Figure 2B to Figure 4C:

Acoustic sensing device 20

Substrates with piezoelectric properties 21

Electrode layer with interdigitated structure 22

Area where sensing material is applied 23

Material layer with protection of electrode properties 24

Microchannel 25

Sensing Circuit 26

Sensors with integrated microfluidics 30

Detailed ways

Please refer to FIG. 1A, FIG. 1B and FIG. 1C, the schematic diagrams of the acoustic wave sensing device with integrated micro-channel of the present invention under the etching side, the acoustic wave sensing device 10 utilizes a substrate 11 with piezoelectric properties, which is electromechanically polished Or chemical etching (chromium gold can be used as an etching mask for etching) processing method to make the thickness of the substrate 11 in a certain substrate area of the substrate 11 smaller than the transmission wavelength of the acoustic wave, and make it possible to generate flat plate flexure waves under the vibration conditions and boundary conditions (or called Lamb wave) sound wave transmission. The substrate area where the thickness of the substrate 11 becomes thinner is used to generate sound waves or stress waves, and the substrate 11 can be used for acoustic wave sensing to detect gas phase or liquid phase molecules by using the phase change of its wave transmission path or the frequency change when it is used as an oscillator. . The advantage of choosing the piezoelectric substrate 11 is that it has better performance in terms of temperature compensation coefficient than the existing piezoelectric film, and the efficiency of the acoustic wave actuation is obtained from the electromechanical coupling coefficient, and the piezoelectric substrate 11 also has a higher Electromechanical coupling coefficient, so its piezoelectric properties are good.

The piezoelectric substrate 11 has quite a lot of conditional control on the growth conditions, and its manufacture is not easy, such as etching is difficult, roughness and etching rate are difficult to control. Therefore, the material of the piezoelectric substrate 11 of the present invention adopts a quartz block (also can be a lithium niobate or a lithium tantalate) as the substrate of the present invention, wherein the quartz block has an excellent temperature compensation coefficient and is not easily affected by temperature. The effect causes a frequency shift.

An electrode layer 12 with a finger-shaped structure is arranged on the front or back of the substrate 11 region with conditions for generating flat plate flexural waves, and the electrode layer 12 with a finger-shaped structure includes two corresponding first electrode layers and a second electrode layer, different finger spacing and other parameters will affect the resonant frequency and other characteristics of the frequency response, and these electrode layers use metal as the structural layer, wherein the first electrode layer and the second electrode layer A sensing material is coated on a transfer path between the electrode layers to form a sensing area 13 coated with the sensing material, which is mainly used for sensing gas-liquid phase molecules and the sensing area 13 of the transfer path. A material layer 14 with electrode characteristic protection, the material layer 14 is made of polymer as material, coated on the first electrode layer and the second electrode layer on the periphery of the electrode layer 12 with interdigitated structure, The protective material layer 14 with electrode characteristics is not coated on the sensing region 13 .

In addition, the acoustic wave sensing device 10 further includes a micro-channel 15 formed by electromechanical grinding or chemical etching in the sensing region 13 under the condition of generating plate flexural waves; thereby forming an acoustic wave sensor with an integrated micro-channel device 10.

In addition to the single-side etching design, the present invention also proposes a double-side etching structure in order to develop immersion or accelerate structure fabrication. Please refer to FIG. 2A , FIG. 2B and FIG. 2C , which are schematic diagrams of the acoustic wave sensing device 20 of the present invention under the two sides of the etching. Similarly, please refer to FIG. 2D and FIG. 2E, the acoustic wave sensing device 20 can also form a micro-flow channel 25 in the sensing area 23 under the condition of generating plate flexural waves by electromechanical grinding or chemical etching; thus forming An acoustic wave sensing device 20 integrated with a micro-channel.

In terms of sensing measurement, the structure is mainly designed as a reference sensing device as shown in FIG. 3A and an acoustic wave sensing device 20 with a sensing layer as shown in FIG. 3B to exclude other influencing factors. In the technology of acoustic wave sensing, because the physical characteristics of plate flexural waves are that when the transmitted wave velocity is lower than the wave velocity of the sensing liquid, the energy will be confined in the transmitted wave and will not be lost, so the acoustic wave sensing device 10 of the present invention For liquid sensing applications, or 20 has better sensitivity than the existing ones, but in combination with fluid sensing, the influence of the interface of the acoustic wave sensing device 10 or 20 integrated with the fluid must be considered. The sensing circuit 26 is used to measure the frequency shift or the phase change of the transmitted wave.

Taking the double-side etching process as an example, please refer to FIG. 4A , FIG. 4B and FIG. 4C . The acoustic wave sensing device 20 of the present invention is not only proposed to be directly processed by the piezoelectric substrate 21, but also because most of the micro-flow channels 25 are also manufactured in the same way, so the same processing method or bonding method can be used at the beginning of the design. Integrate the micro-channel 25 on the same substrate 21 with piezoelectric properties, and further form the acoustic wave sensing device 20 array and the micro-channel 25 to form an acoustic wave with a micro-channel comprising more than two acoustic wave sensing devices 20 of the present invention. Sensor 30 wafer.

Please refer to FIG. 5 . FIG. 5 is a flow chart of the manufacturing method of the acoustic wave sensing device of the present invention. The manufacturing method of the acoustic wave sensing device 10 or 20 of the present invention comprises the following steps: firstly, by electromechanical grinding or chemical etching, a single-sided or double-sided processing method is used to make a certain region on a piezoelectric characteristic substrate 11 or 21 The thickness of the substrate 11 or 21 is smaller than the propagation wavelength of the acoustic wave, and the region of the substrate 11 or 21 is provided with conditions for generating plate flexural waves (step 500 ).

Then form an electrode layer 12 or 22 with an interdigitated structure on the substrate 11 or 21 with plate flexural wave conditions (step 502), wherein the electrode layer 12 or 22 with an interdigitated structure includes two phases Then measure the frequency response of a corresponding first electrode layer and a second electrode layer; moreover, if step 500 adopts a single-sided processing method, then the electrode layer 12 with a finger-like structure will The front side, the back side, or both sides of the substrate 10 area are carried out.

Then apply a sensing material on a transmission path between the electrode layer 12 or 22 with the interdigitated structure to form a sensing area 13 or 23, wherein the sensing material can be coated on the interdigitated structure. The electrode layer 12 or 22 is coated on the same side, the opposite side or both sides simultaneously (step 504 ). Finally, an electrode protective material layer 14 or 24 is coated on the first electrode layer and the second electrode layer on the electrode layer 12 or 22 with a finger-like structure, and the protective material layer 14 with electrode characteristics is not coated. or 24 on the sensing region 13 or 23 (step 506).

Please refer to FIG. 6 . FIG. 6 is a flow chart of the manufacturing method of the acoustic wave sensing device with micro-channels of the present invention. After step 506, it may further include: forming a micro-channel 15 or 25 in the sensing region 13 or 23 under the condition of generating plate flexural waves by means of electromechanical grinding or chemical etching (step 508); thus, forming a Acoustic sensing device 10 or 20 with integrated microfluidic channels. Wherein step 508 and step 500 can be performed simultaneously.

The present invention provides an acoustic wave sensing device with an integrated micro-channel and a method thereof, which utilizes new element manufacturing and design to produce an element with good piezoelectric properties, stable temperature compensation characteristics, and firm structure, which will make the flat plate flex Curve waves can be applied to liquid state sensors. In particular, the present invention can form two cavities on the substrate by means of double-sided processing, and achieve a thin film state in the central diaphragm; the design of the micro-channel is conducive to the drainage of the fluid to be measured to the sensing area, and accelerates the sensing film and The reaction of the analyte can be connected with other external components; at the same time, the present invention can be integrated in biochemical detection applications and array detection to obtain analysis and detection data simultaneously.

In summary, it is only a detailed description and illustration of a preferred embodiment of the present invention, and does not limit the patent scope of this creation. Therefore, all equivalent changes made by using the instructions and illustrations of this creation are implemented. For example, they are all included in the scope of this creation in the same way, and any changes or modifications that can be easily conceived by anyone familiar with the art in the field of the invention can be covered by the scope of the claims of this case.

Claims (27)

1. A kind of acoustic wave sensing device, is characterized in that, this acoustic wave sensing device comprises: A substrate with piezoelectric properties, the substrate thickness of a certain substrate area of the substrate is made smaller than the wavelength of the acoustic wave transmission by electromechanical or chemical processing, and it has the conditions to generate flat plate flexure waves; An electrode layer with interdigitated structure is arranged on the front or back side of the substrate area with conditions for generating plate flexural waves, and the electrode layer with interdigitated structure includes two corresponding first electrode layers and a second electrode layer, wherein a sensing material is coated on a transfer path between the first electrode layer and the second electrode layer to form a sensing region; and A material layer with electrode characteristic protection is coated on the periphery of the first electrode layer and the second electrode layer. 2 . The acoustic wave sensing device as claimed in claim 1 , wherein the region of the substrate forming a thin plate generates acoustic waves or stress wave transmissions for acoustic sensing of gas phase or liquid phase molecules. 3 . 3 . The acoustic wave sensing device according to claim 1 , wherein the piezoelectric substrate is made of quartz, lithium niobate or tantalum niobate. 4 . 4 . The acoustic wave sensing device as claimed in claim 1 , wherein the substrate having piezoelectric properties is thinned by electromechanical grinding to reduce the thickness of the certain substrate region. 5 . 5 . The acoustic wave sensing device according to claim 1 , wherein the substrate with piezoelectric properties is chemically etched to make the substrate thickness of a certain substrate region thinner. 6 . 6. The acoustic wave sensing device according to claim 1, wherein the processing method of the substrate with piezoelectric characteristics is a single-side processing or double-side processing method, and the substrate thickness of the certain substrate region Thinned. 7 . The acoustic wave sensing device according to claim 1 , wherein the electrode layer with interdigitated structure uses metal as the structural layer. 8 . The acoustic wave sensing device according to claim 1 , wherein the material layer with electrode characteristic protection is made of high molecular polymer. 9. The acoustic wave sensing device according to any one of claims 1-8, further comprising a microfluidic channel, electromechanically or formed by chemical processing. 10. The acoustic wave sensing device according to claim 9, wherein the micro-channel is processed by chemical etching. 11. The acoustic wave sensing device according to claim 9, wherein the micro-channel is processed by electromechanical grinding. 12. A method of manufacturing an acoustic wave sensing device, characterized in that the method comprises the following steps: Make the substrate thickness of a certain region on a substrate with piezoelectric characteristics smaller than the transmission wavelength of the acoustic wave, and make the substrate region have the conditions to generate flat plate flexure waves; forming an electrode layer with a finger-shaped structure on the substrate region with flat plate flexural wave conditions; Coating a sensing material on a transfer path between the interdigitated electrode layers to form a sensing region; and Coating an electrode protection material around the electrode layer with interdigitated structure. 13 . The manufacturing method of the acoustic wave sensing device according to claim 12 , wherein the substrate with piezoelectric properties is made of quartz, lithium niobate or tantalum niobate. 14 . 14. The method for manufacturing an acoustic wave sensing device as claimed in claim 12, wherein the step of making the substrate thickness of a certain area on a substrate with piezoelectric characteristics smaller than the wavelength of the acoustic wave transmission is to change the thickness of the substrate by electromechanical grinding. Thin. 15. The method for manufacturing an acoustic wave sensing device as claimed in claim 12, wherein the step of making the substrate thickness of a certain area on a substrate with piezoelectric characteristics smaller than the wavelength of the acoustic wave transmission is to change the thickness of the substrate by chemical etching. Thin. 16. The method for manufacturing an acoustic wave sensing device as claimed in claim 12, wherein the step of making the substrate thickness of a certain region on a substrate with piezoelectric characteristics smaller than the transmission wavelength of the acoustic wave is performed by single-side processing or double-side processing way to make the thickness of the substrate thinner. 17. The method of manufacturing an acoustic wave sensing device as claimed in claim 16, wherein when a single-side processing method is adopted, the electrode layer with interdigitated structure is placed on the front side of the substrate region with flat plate flexural wave conditions , the back or both sides of the formation. 18. The method for manufacturing an acoustic wave sensing device as claimed in claim 12, wherein the electrode layer having an interdigitated structure uses metal as a structural layer. 19 . The method of manufacturing an acoustic wave sensing device according to claim 12 , wherein the electrode layer having an interdigitated structure includes two corresponding first electrode layers and a second electrode layer. 19 . 20. The method for manufacturing an acoustic wave sensing device according to claim 12, wherein the sensing material is coated on the same side, the opposite side, or both sides of the electrode layer with the interdigitated structure . 21. The manufacturing method of the acoustic wave sensing device as claimed in claim 12, wherein the material layer having electrode characteristic protection is made of high molecular polymer. 22. The method for manufacturing an acoustic wave sensing device according to claim 12, further comprising the following steps: forming a microfluidic channel in the sensing region under the condition of generating plate flexural waves; Thus, an acoustic wave sensing device with integrated micro-channel is formed. 23. The method for manufacturing an acoustic wave sensing device according to claim 22, wherein the micro-channel is formed by chemical etching. 24. The method for manufacturing an acoustic wave sensing device according to claim 22, wherein the micro-channel is formed by electromechanical grinding. 25. The manufacturing method of an acoustic wave sensing device as claimed in claim 22, wherein the step of forming a microfluidic channel in the sensing region under the condition of generating plate flexural waves is the same as making a piezoelectric The step that the thickness of the substrate in a certain area on the characteristic substrate is smaller than the wavelength of the acoustic wave transmission is performed simultaneously. 26. An acoustic wave sensor, characterized in that it comprises two or more acoustic wave sensing devices as claimed in claim 1, each acoustic wave sensing device is fabricated on the same substrate with piezoelectric properties. 27. The acoustic wave sensor according to claim 26, wherein each acoustic wave sensing device is formed by integrating more than two acoustic wave sensing devices and micro-channels by bonding.

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