KR-20260063620-A - High sensitivity gas concentration sensor with suspended structure heater and Method of manufacturing thereof

KR20260063620AKR 20260063620 AKR20260063620 AKR 20260063620AKR-20260063620-A

Abstract

The high-sensitivity gas concentration sensor equipped with a suspension structure heater according to the present invention comprises: a substrate; a micro heater provided on the substrate and heated as current is applied; a sensor part provided on the substrate and capable of measuring the temperature of the micro heater; and an etching space formed by etching is provided at the bottom of the micro heater. The method for manufacturing the high-sensitivity gas concentration sensor equipped with a suspension structure heater according to the present invention comprises: a substrate preparation step; a metal thin film deposition step; a photoresist stacking step; a curing step of curing the photoresist along the pattern of the micro heater by exposing it to light; an etching step of fabricating the micro heater by etching the photoresist and the metal thin film; and an etching space formation step of forming an etching space at the bottom of the micro heater by etching the area around the micro heater after the etching step.

Inventors

오동욱
전창의
김호성

Assignees

조선대학교산학협력단

Dates

Publication Date: 20260507
Application Date: 20241030

Claims (14)

In a sensor for measuring gas concentration, Substrate; A micro heater provided on the above substrate and heated as current is applied; A sensor unit provided on the above substrate and capable of measuring the temperature of the micro heater; A high-sensitivity gas concentration sensor equipped with a suspension structure heater, characterized in that the lower part of the above-mentioned micro heater is provided with an etched space formed by etching.
In paragraph 1, Both sides of the above micro heater are supported by the substrate, and A high-sensitivity gas concentration sensor equipped with a suspension structure heater, characterized in that the above-mentioned etching space is provided at the lower part of the center of the micro heater.
In paragraph 1, A high-sensitivity gas concentration sensor equipped with a suspension structure heater, characterized in that the above-mentioned etching space is formed by wet etching.
In paragraph 3, The above wet etching solution is, A high-sensitivity gas concentration sensor equipped with a suspension structure heater characterized by being composed of any one of potassium hydroxide ( KOH ), tetramethylammonium hydroxide (TMAH), sulfuric acid ( H₂SO₄ ), hydrogen peroxide ( H₂O₂ ), hydrochloric acid (HCl), hydrofluoric acid (HF), perchloric acid, chromic acid, and NMP (N-Methyl-2-pyrrolidone).
In paragraph 1, The above etching space is, A high-sensitivity gas concentration sensor equipped with a suspension structure heater characterized by being etched to an etching thickness of 5㎛ to 20㎛.
In paragraph 1, The above substrate is, A high-sensitivity gas concentration sensor equipped with a suspension structure heater characterized by being made of any one of polyethylene naphthalate, polyethylene terephthalate, polyphenylene sulfide, polyisobutylene, polyethersulfone, poly(p-phenylene benzobisoxazole), kapton, polycarbonate, silicon, quartz, Pyrex, and EXG (Eagle XG glass).
In paragraph 1, The above micro heater is, A high-sensitivity gas concentration sensor equipped with a suspension structure heater characterized by being made of any one of aluminum, nickel, chromium, titanium, carbon, indium tin oxide (ITO), gold, and platinum.
In a method for manufacturing a sensor for measuring gas concentration, Substrate preparation step; A metal thin film deposition step of depositing a metal thin film on the upper surface of the above substrate; A photoresist deposition step of depositing a photoresist layer over the metal thin film deposited in the metal thin film deposition step; A curing step in which a photomask is placed along the pattern of a microheater over the photoresist layer stacked in the above photoresist stacking step, and the photoresist is cured along the pattern of the microheater by exposing it to light; An etching step for fabricating the micro heater by etching the uncured photoresist and metal thin film in the above curing step; A method for manufacturing a high-sensitivity gas concentration sensor equipped with a suspension structure heater, characterized by including: an etching space forming step in which the area around the micro heater is etched after the above etching step to form an etching space at the bottom of the micro heater.
In paragraph 8, Both sides of the above micro heater are supported by the substrate, and A method for manufacturing a high-sensitivity gas concentration sensor equipped with a suspension structure heater, characterized in that the above-mentioned etching space is provided at the lower part of the center of the above-mentioned micro heater.
In paragraph 8, The above etching space formation step is, A method for manufacturing a high-sensitivity gas concentration sensor equipped with a suspension structure heater, characterized by wet etching the area around the micro heater.
In Paragraph 10, The above wet etching solution is, A method for manufacturing a high-sensitivity gas concentration sensor equipped with a suspension structure heater, characterized by being composed of any one of potassium hydroxide ( KOH ), tetramethylammonium hydroxide ( TMAH ), sulfuric acid ( H₂SO₄ ), hydrogen peroxide (H₂O₂), hydrochloric acid (HCl), hydrofluoric acid (HF), perchloric acid, chromic acid, and NMP (N-Methyl-2-pyrrolidone).
In paragraph 8, The above etching space is, A method for manufacturing a high-sensitivity gas concentration sensor equipped with a suspension structure heater characterized by being etched to an etching thickness of 5㎛ to 20㎛.
In paragraph 8, The above substrate is, A method for manufacturing a high-sensitivity gas concentration sensor equipped with a suspension structure heater, characterized by being made of any one of polyethylene naphthalate, polyethylene terephthalate, polyphenylene sulfide, polyisobutylene, polyethersulfone, poly(p-phenylene benzobisoxazole), kapton, polycarbonate, silicon, quartz, Pyrex, and EXG (Eagle XG glass).
In paragraph 8, The above metal thin film is, A method for manufacturing a high-sensitivity gas concentration sensor equipped with a suspension structure heater characterized by being made of any one of aluminum, nickel, chromium, titanium, carbon, indium tin oxide (ITO), gold, and platinum.

Description

High sensitivity gas concentration sensor with suspended structure heater and Method of manufacturing thereof The present invention relates to a high-sensitivity gas concentration sensor equipped with a suspension structure heater and a method for manufacturing a high-sensitivity gas concentration sensor equipped with a suspension structure heater. More specifically, the invention relates to a high-sensitivity gas concentration sensor equipped with a suspension structure heater and a method for manufacturing a high-sensitivity gas concentration sensor equipped with a suspension structure heater, wherein the sensitivity of the sensor can be improved by providing an etching space at the bottom of a microheater that measures gas concentration through temperature change. Recently, various gas concentration sensors have been developed, and these sensors can measure gas concentration using various methods. Gas concentration sensors can measure gas concentration through electrochemical methods utilizing the conductivity of solutions, optical methods utilizing infrared absorption, and methods measuring the electrical resistance of nanoparticles or nanowires. Among the methods for measuring gas concentration using a gas concentration sensor, a method is used in which a microheater is placed on a substrate and heated using an alternating current to measure the gas concentration through the thermal conductivity based on the temperature change around the microheater. Specifically, when a microheater is heated through an alternating current, the thermal conductivity can be determined according to the concentration of the surrounding gas, and the amplitude of the temperature change measured by the microheater can be determined by the thermal conductivity. In this way, by measuring temperature changes around the microheater, it becomes possible to predict the type of unmixed gas based on the known thermal conductivity of the substrate or calculate the concentration of a mixed gas of known type. Sensitivity can be a critical factor in determining the performance of gas concentration sensors. Therefore, research and development aimed at increasing measurement sensitivity in gas concentration sensors is continuously underway. To increase the measurement sensitivity of gas concentration sensors, methods are being studied to minimize heat loss from the microheater toward the substrate, and substrates with low thermal conductivity have been used for this purpose. However, using such low-thermal-conductivity substrates presents problems such as difficulty in securing sufficient sensitivity, complicated manufacturing processes, and low sensor durability. This invention was created to solve such problems. This invention (result) is the result of the Local Government-University Cooperation-based Regional Innovation Project conducted in 2024 with funding from the Ministry of Education and support from the National Research Foundation of Korea. (Project Management No.: 2021RIS-002, Contribution Rate: 2/4) This invention (result) is the result of a project by the Industry-Academic Cooperation Foundation of Chosun University, funded by the Ministry of Science and ICT and supported by the National Research Foundation of Korea. (Project Management No.: RS-2022-00144368, Contribution Rate: 1/4) This invention (result) is the result of a project by the Industry-Academic Cooperation Foundation of Chosun University, funded by the Ministry of Trade, Industry and Energy and supported by the National Research Foundation of Korea. (Project Management No.: RS-2022-00144368, Contribution Rate: 1/4) FIG. 1 is a drawing showing a high-sensitivity gas concentration sensor equipped with a suspension structure heater according to an embodiment of the present invention. FIG. 2 is a drawing showing that an etching space is formed in the lower part of a micro heater according to an embodiment of the present invention. FIG. 3 is a diagram showing the comparison of temperature amplitudes by measuring the helium (He) concentration in the air through a gas concentration sensor having an etching space formed at the bottom of a micro heater according to an embodiment of the present invention and a gas concentration sensor in which the micro heater is in contact with a polyimide substrate. FIG. 4 is a diagram showing the temperature amplitude according to the etched thickness when the frequency of the alternating current applied to the micro heater according to an embodiment of the present invention is 10 kHz and 20 kHz. FIG. 5 is a diagram showing the minimum thickness of an etching space in which the sensitivity of a gas concentration sensor is enhanced to a specified level according to the frequency of the alternating current applied to a micro heater according to an embodiment of the present invention. FIG. 6 is a drawing showing a method for manufacturing a high-sensitivity gas concentration sensor equipped with a suspension structure heater according to an