阅读说明：本技术 一种基于墨滴打印的mems气体敏感结构及其制备方法 (MEMS gas sensitive structure based on ink drop printing and preparation method thereof ) 是由 刘宇航 汪震海 张晨生 彭渤 许诺 于 2020-10-30 设计创作，主要内容包括：一种基于墨滴打印的MEMS气体敏感结构及其制备方法,气体敏感结构包括衬底、金属电极层和气敏层,气敏层为在衬底上连接所述各金属电极交叠处的金属电极端部的线状结构,通过将气敏材料溶液化,并通过精密打印喷头在所述正电极和负电极交叠区域以确定的步长滴涂而形成气敏材料薄膜。本发明的方案不依赖于金属电极之间的间距即可实现更小的结构线宽和更优的灵敏度,由于墨滴的量、打印喷墨的位置和喷头移动的步长可精确控制,因此在基于该方法制成重复性好、尺寸精度较高的气敏层,有利于MEMS气体敏感结构的批量化和低成本化制备。(An MEMS gas sensitive structure based on ink drop printing and a preparation method thereof are provided, the gas sensitive structure comprises a substrate, a metal electrode layer and a gas sensitive layer, the gas sensitive layer is a linear structure which is connected with the end part of a metal electrode at the overlapping part of each metal electrode on the substrate, and a gas sensitive material film is formed by dissolving a gas sensitive material and performing drip coating in a determined step length in the overlapping area of a positive electrode and a negative electrode through a precise printing spray head. The scheme of the invention can realize smaller structure line width and better sensitivity without depending on the distance between metal electrodes, and because the amount of ink drops, the position of printing ink jet and the moving step length of a spray head can be accurately controlled, a gas-sensitive layer with good repeatability and higher dimensional precision is manufactured based on the method, thereby being beneficial to the batch and low-cost preparation of the MEMS gas-sensitive structure.)

1. An MEMS gas sensitive structure based on ink drop printing comprises a substrate, a metal electrode layer and a gas sensitive layer, wherein the substrate is a surface oxidation layer of a silicon wafer or an insulation material based on flexibility, the metal electrode is formed on the substrate after sputtering-patterning-corrosion process, the metal electrode comprises a positive electrode and a negative electrode, the positive electrode and the negative electrode are arranged oppositely and are partially overlapped at the end part of the electrode, the metal electrode is made of a metal material with excellent conductivity, preferably, the metal electrode is made of gold, silver or aluminum, the gas sensitive layer is a linear structure connecting the end parts of the metal electrodes at the overlapped part of the metal electrodes on the substrate, a gas sensitive material film is formed by dissolving the gas sensitive material and dispensing in a determined step size at the overlapped part of the positive electrode and the negative electrode through a precision printing nozzle, the gas sensitive material film is in physical contact with the metal electrode and the substrate.

2. Droplet printing based MEMS gas sensitive structure according to claim 1, the metal electrodes being metal comb-tooth electrodes, the positive and negative electrodes each being comb-tooth shaped and partially overlapping at an end position.

3. Droplet printing based MEMS gas-sensitive structure according to claim 2, the substrate being SiO₂Or other insulating material.

4. A droplet printing based MEMS gas sensitive structure according to claim 3, wherein the thickness of the metal electrode is between about 50nm and about 100 nm.

5. The droplet printing based MEMS gas-sensitive structure of any one of claims 1-4, the gas-sensitive material being solubilized into droplets.

6. Droplet printing based MEMS gas sensitive structure according to any of claims 1-5, wherein the determined step size is a minimum step size for precise control of the movement of the jet.

7. A preparation method of a MEMS gas sensitive structure based on ink droplet printing comprises the following steps:

preparing a metal electrode layer on a substrate, matching with a mask plate, and processing and forming through a photoresist-homogenizing, photoetching, developing and stripping process, wherein the metal electrode comprises a positive electrode and a negative electrode which are oppositely arranged and partially overlapped at the end part of the electrode;

preparing a gas-sensitive layer on the metal electrode layer, firstly preparing a gas-sensitive material solution, dissolving a gas-sensitive material in a solvent according to a determined ratio, fully dissolving the gas-sensitive material by ultrasonic oscillation, wherein the dissolved gas-sensitive material is ink, then putting the prepared ink into an ink cavity of a precision printing device, wherein the printing device can precisely control the amount of the ink sprayed each time, and processing the gas-sensitive layer by a printing process;

thirdly, testing the conductivity between every two adjacent metal electrodes, if the situation that every two adjacent metal electrodes are not communicated exists, repeating the printing process between the two metal electrodes until the two metal electrodes are electrically communicated, and finally forming a complete gas sensitive structure;

and fourthly, drying and aging the gas sensitive structure, and dissolving and removing redundant gas sensitive materials through a solvent. And introducing dry nitrogen to the surface of the MEMS gas sensitive structure, heating to 60-150 ℃, keeping for two hours, and finishing the step to finish the preparation of the MEMS gas sensitive structure.

8. A method of making a droplet printing based MEMS gas sensitive structure according to claim 7, said metal electrodes being metal comb electrodes, the positive and negative electrodes each being comb-toothed and partially overlapping at end positions.

9. The method for preparing an MEMS gas sensitive structure based on ink droplet printing according to claim 7 and 8, wherein in the second step, the gas sensitive layer is processed by a printing process by using the edge of the overlapped area of the metal electrodes as a starting point, aligning a nozzle to the area, starting printing, moving the nozzle in a direction perpendicular to the extending direction of the metal electrodes by a step size of about the diffusion radius of the ink droplets, repeating the printing process until the ink droplets cover all the metal electrodes, and forming an approximately linear gas sensitive thin layer connecting the positive electrode and the negative electrode on the substrate.

10. A method of fabricating droplet printing based MEMS gas sensitive structures according to any of claims 7-9, wherein the heating step in the fourth step is performed in a temperature controlled box.

Technical Field

The invention belongs to the technical field of gas detection, and relates to an MEMS gas sensitive structure based on ink drop printing and a preparation method thereof.

Background

The gas sensor is an important component in the technical field of MEMS (micro electro Mechanical Systems) sensing, the gas sensitive structure is a key component for realizing the function of the gas sensor, and the structure and the process design of the gas sensor have decisive influence on the performance of the gas sensor. The line width of the MEMS gas-sensitive structure, i.e. the smallest planar dimension over which the gas-sensitive material can effectively act, such as the smallest distance between a pair of electrodes that are filled with the gas-sensitive material, has a large and direct effect on its sensitivity, because a smaller line width means that the amount of gas-sensitive material carried by the equivalent smallest gas-sensitive unit is also reduced, and the relative amount of change that occurs during operation will become more significant, and therefore, reducing the line width is generally beneficial to improving the sensitivity to gas. However, merely reducing the line width generally does not directly result in improved performance because, on the one hand, the minimum line width is limited by the MEMS processing technology; on the other hand, too small a line width deteriorates reliability, and when the line width is smaller than conductive impurity particles in the environment, these particles are liable to cause functional failure of the gas-sensitive structure, as shown in fig. 1a, 1 b.

Aiming at the problems of the traditional gas sensitive structure, the invention provides a novel gas sensitive structure and a preparation method thereof, which are based on the printing principle and can effectively improve the sensitivity of the gas sensitive structure on the premise of not excessively reducing the distance between metal electrodes. In addition, the preparation method is simple, convenient and good in repeatability, and has advantages in cost, performance and reliability.

Disclosure of Invention

An MEMS gas sensitive structure based on ink drop printing comprises a substrate, a metal electrode layer and a gas sensitive layer, wherein the substrate is a surface oxide layer of a silicon wafer or a flexible-based insulating material, the metal electrode is formed on the substrate by sputtering, patterning and etching processes, the metal electrode comprises a positive electrode and a negative electrode which are oppositely arranged, and partially overlapped at the end position of the electrode, the metal electrode is made of metal material with excellent conductive performance, the gas-sensitive layer is a linear structure which is connected with the end parts of the metal electrodes at the overlapped part of the metal electrodes on the substrate, and forming a gas-sensitive material film by solubilizing the gas-sensitive material and dripping the gas-sensitive material film in a determined step length in an overlapped area of the positive electrode and the negative electrode through a precision printing spray head, wherein the gas-sensitive material film is in physical contact with the metal electrode and the substrate.

According to the MEMS gas sensitive structure based on ink drop printing, the metal electrode is a metal comb tooth electrode, and the positive electrode and the negative electrode are both in a comb tooth shape and are partially overlapped at the end position.

According to the MEMS gas sensitive structure based on ink drop printing, the substrate is SiO₂Or other insulating material.

According to the droplet printing based MEMS gas sensitive structure of the present invention, the metal electrode is made of gold, silver or aluminum.

According to the MEMS gas sensitive structure based on ink drop printing, the thickness of the metal electrode is about 50nm-100 nm.

According to the MEMS gas sensitive structure based on ink drop printing, the gas sensitive material is solubilized into ink drops.

According to the MEMS gas sensitive structure based on ink drop printing, the determined step size is the minimum step size for accurately controlling the movement of the spray head.

A preparation method of a MEMS gas sensitive structure based on ink droplet printing comprises the following steps:

preparing a metal electrode layer on a substrate, matching with a mask plate, and processing and forming through a photoresist-homogenizing, photoetching, developing and stripping process, wherein the metal electrode comprises a positive electrode and a negative electrode which are oppositely arranged and partially overlapped at the end part of the electrode;

preparing a gas-sensitive layer on the metal electrode layer, namely preparing a gas-sensitive material solution, dissolving the gas-sensitive material in a solvent according to a determined ratio, and fully dissolving the gas-sensitive material by ultrasonic oscillation, wherein the dissolved gas-sensitive material is ink; then, the prepared ink is put into an ink cavity of a precise printing device, and the printing device can precisely control the amount of the ink sprayed each time; processing the gas-sensitive layer by a printing process;

thirdly, testing the conductivity between every two adjacent metal electrodes, if the situation that every two adjacent metal electrodes are not communicated exists, repeating the printing process between the two metal electrodes until the two metal electrodes are electrically communicated, and finally forming a complete gas sensitive structure;

and fourthly, drying and aging the gas sensitive structure, and dissolving and removing redundant gas sensitive materials through a solvent. And introducing dry nitrogen to the surface of the MEMS gas sensitive structure, heating to 60-150 ℃, keeping for two hours, and finishing the step to finish the preparation of the MEMS gas sensitive structure.

According to the preparation method of the MEMS gas sensitive structure based on ink drop printing, the metal electrode is a metal comb tooth electrode, and the positive electrode and the negative electrode are both in a comb tooth shape and are partially overlapped at the end position.

According to the preparation method of the MEMS gas sensitive structure based on ink drop printing, in the second step, the specific method for processing the gas sensitive layer through the printing process is that the edge of the overlapped area of the metal electrodes is used as a starting point, a spray head is aligned to the area and starts to print, the movement direction of the spray head is perpendicular to the extending direction of the metal electrodes, the moving step length is about the diffusion radius of the ink drops, the printing process is repeated until the ink drops cover all the metal electrodes, and the approximately linear gas sensitive thin layer connected with the positive electrode and the negative electrode is formed on the substrate.

According to the preparation method of the MEMS gas sensitive structure based on ink drop printing, the heating step in the fourth step is carried out in a temperature control box.

The invention has the beneficial effects that:

the MEMS gas sensitive structure is prepared based on an ink drop printing process, smaller structure line width and better sensitivity can be realized without depending on the distance between metal electrodes, and because the amount of ink drops, the position of printing ink jet and the moving step length of a spray head can be accurately controlled, a gas sensitive layer with good repeatability and higher dimensional precision is prepared based on the method, and the mass and low-cost preparation of the MEMS gas sensitive structure is facilitated. In addition, the gas sensitive layer manufactured based on micro-droplet printing has good thickness controllability, the thickness of the gas sensitive layer can be effectively reduced, and the response speed of the gas sensitive structure to gas is further improved.

Drawings

FIG. 1a, FIG. 1b are prior art schematic diagrams of a MEMS gas-sensitive structure;

FIG. 2 is a general schematic view of a droplet printing based MEMS gas sensitive structure of the present invention;

FIG. 3 is a schematic diagram of a metal electrode layer of an ink drop printing based MEMS gas sensitive structure of the present invention;

FIG. 4 is a schematic diagram of the steps for preparing the gas-sensitive layer of the droplet-printed MEMS gas-sensitive structure of the present invention;

FIG. 5 is a schematic diagram of the step length of the print head in the step of preparing the gas-sensitive layer of the MEMS gas-sensitive structure based on ink drop printing according to the present invention;

FIG. 6 is a schematic diagram of the conductivity testing steps for a droplet printing based MEMS gas sensitive structure of the present invention;

FIG. 7 is a flow chart of a method of fabricating a droplet printing based MEMS gas sensitive structure of the present invention.

Detailed Description

The invention will be further illustrated with reference to the following specific examples. It should be understood that the examples are only for illustrating the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that various changes or modifications can be made by those skilled in the art after reading the disclosure of the present invention, and such equivalents also fall within the scope of the invention.

An ink drop printing-based MEMS gas sensitive structure as shown in FIG. 2 comprises a substrate 1, a metal electrode layer 2 and a gas sensitive layer 3, wherein the substrate 1 is a surface oxide layer of a silicon wafer or a flexible based insulating material, such as SiO₂. The metal electrode 2 is formed on the substrate by sputtering, patterning and etching processes. Metal electric machineThe poles 2 comprise a positive electrode 2.1 and a negative electrode 2.2, said positive electrode 2.1 and negative electrode 2.2 being arranged opposite and partially overlapping at the end positions of the electrodes. The metal electrode 2 is made of metal material with excellent conductivity such as gold, silver or aluminum, and the thickness of the metal electrode 2 is about 50nm-100 nm. The gas-sensitive layer 3 is a linear structure which is connected with the end parts of the metal electrodes at the overlapped parts of the metal electrodes 2 on the substrate 1, a gas-sensitive material is converted into ink drops, and the ink drops are dripped and coated in the overlapped area of the positive electrode 2.1 and the negative electrode 2.2 by a precision printing nozzle in the minimum step length for precisely controlling the movement of the nozzle to form a gas-sensitive material film 3, wherein the gas-sensitive material film 3 is in physical contact with the metal electrodes 2 and the substrate 1. In the present embodiment, the metal electrode is a metal comb electrode, but in practical application, the metal electrode is not limited to such an electrode.

Fig. 7 shows a method for preparing the MEMS gas-sensitive structure based on droplet printing, which includes:

in the first step, as shown in fig. 3, a metal electrode layer 2 is prepared on a substrate 1, and is matched with a mask plate, and is formed by a photoresist mask development stripping process, wherein the metal electrode 2 comprises a positive electrode 2.1 and a negative electrode 2.2, the positive electrode 2.1 and the negative electrode 2.2 are oppositely arranged, and are partially overlapped at the end position of the electrode. In the present embodiment, metal comb electrodes are used, but in practical applications, the electrodes are not limited to such electrodes.

Secondly, as shown in fig. 4, preparing a gas-sensitive layer 3 on the metal electrode layer 2, firstly preparing a gas-sensitive material solution, dissolving the gas-sensitive material in a solvent according to a determined proportion, and fully dissolving the gas-sensitive material by ultrasonic oscillation, wherein the dissolved gas-sensitive material is ink; then, the prepared ink is put into an ink cavity of a precise printing device, and the printing device can precisely control the amount of the ink sprayed each time; the gas-sensitive layer 3 is processed by a printing process. The specific method for processing the gas-sensitive layer by the printing process comprises the steps of taking the edge of the overlapping area of the metal comb teeth electrode as a starting point, aligning a spray head to the area, starting printing, enabling the motion direction of the spray head to be perpendicular to the direction of the comb teeth, enabling the moving step length to be about the ink drop diffusion radius (as shown in figure 5), repeating the printing process until the ink drops cover all the comb teeth electrodes 2, and forming an approximately linear gas-sensitive thin layer 3 connected with the positive electrode 2.1 and the negative electrode 2.2 on the substrate 1.

Thirdly, as shown in fig. 6, testing the conductivity between each two adjacent metal comb electrodes (A, B, C, D, E, F, G, H, I, J), if the two adjacent metal comb electrodes are not communicated, repeating the printing process between the two metal comb electrodes until the two metal comb electrodes are electrically communicated, and finally forming a complete gas sensitive structure;

and fourthly, drying and aging the gas sensitive structure, and dissolving and removing redundant gas sensitive materials through a solvent. And introducing dry nitrogen to the surface of the MEMS gas sensitive structure, heating to 60-150 ℃, wherein the heating can be carried out in a temperature control box and is kept for two hours, and the preparation of the MEMS gas sensitive structure is finished after the step is finished.

The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiment. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.