KR-102963394-B1 - GAS SENSOR AND FABRICATION METHOD FOR THE SAME

KR102963394B1KR 102963394 B1KR102963394 B1KR 102963394B1KR-102963394-B1

Abstract

A gas sensor that senses specific gas molecules or compounds, with improved sensing deviation and excellent sensing performance, and a method for manufacturing the same are introduced.

Inventors

권대성
유일선
이장현
김동구
김현수

Assignees

현대자동차주식회사
기아 주식회사

Dates

Publication Date: 20260508
Application Date: 20210503

Claims (12)

A step of forming a groove on one side of the upper surface of a substrate; A step of forming a first insulating layer on the other side of the upper surface of the substrate; Step of forming a first sensing material in the groove; A step of forming an electrode on the upper surface of a first insulating layer, wherein the electrode is extended to be electrically connected to a first sensing material; Step of forming a second insulating layer on the upper surface of the electrode; A step of forming a heater on the upper surface of the second insulating layer; and A method for manufacturing a gas sensor comprising the step of forming a sensing space below the first sensing material by etching a point on the upper part of the substrate where the first sensing material is formed.
In claim 1, After the step of forming a first sensing material in the groove, A method for manufacturing a gas sensor characterized by further including the step of forming a second sensing material on top of a first sensing material so that the second sensing material is positioned between the first sensing material and the electrode.
In claim 2, A method for manufacturing a gas sensor characterized in that the first sensing material and the second sensing material are selected from one or more of the group consisting of SnO2 , TiO2 , WO3 , Pt, and Pd.
In claim 2, A method for manufacturing a gas sensor characterized in that a second sensing material functions as a sensing material for sensing gas, and a first sensing material functions as a functionalization treatment material for functionalizing the second sensing material.
In claim 1, A method for manufacturing a gas sensor characterized in that, in the step of forming a groove, the groove is formed by lithography and etching processes.
In claim 1, A method for manufacturing a gas sensor characterized in that the first insulating layer and the second insulating layer comprise one or more of SiO2 , Si3N4 .
In claim 1, In the step of forming a sensing space, A method for manufacturing a gas sensor characterized by etching a portion of the substrate using XeF2 .
In claim 1, A method for manufacturing a gas sensor characterized by the depth of a groove formed on one side of the upper surface of a substrate being 0.1 nm to 100 nm.
In claim 1, After the step of forming a second insulating layer on the upper surface of the electrode, A method for manufacturing a gas sensor characterized by further including the step of forming via holes and electrode pads on the upper surface of a second insulating layer and electrically connecting the electrode and the electrode pads.
Substrate; A first sensing material layer disposed on one side of the upper surface of a substrate; A sensing space formed between the first sensing material layer and the top of the substrate by etching a point on the substrate where the first sensing material layer is disposed; A first insulating layer provided on the other side of the upper surface of the substrate; An electrode formed on the top of the first insulating layer and electrically connected to the first sensing material layer; A second insulating layer formed on the upper surface of the electrode; and A gas sensor comprising a heater formed on the upper surface of a second insulating layer.
In claim 10, A gas sensor characterized by having a second sensing material layer formed on the upper surface of a first sensing material layer, wherein the second sensing material layer is disposed between the first sensing material layer and an electrode.
In claim 10, A via hole formed on the upper surface of the second insulating layer; and A gas sensor characterized by further including an electrode pad electrically connected to an electrode through a via hole.

Description

Gas Sensor and Fabrication Method for the Same The present invention relates to a gas sensor. Specifically, it relates to a gas sensor in which a heater and a sensing material are integrated on a thin film based on silicon through a MEMS process, characterized in that the sensing material is located at the bottom of the membrane. Gas sensors are used to detect specific molecules or compounds within a gas to determine whether those molecules or compounds are leaking. Among these gas sensors, MEMS sensors are fabricated by forming an insulating layer to prevent current flow on a substrate such as a silicon wafer and patterning electrodes and sensing materials. Since the sensing material that reacts with the gas to be detected has the advantage of increasing reactivity with the target gas or increasing the reaction and recovery speeds at high temperatures, a heater is sometimes integrated into the sensor during fabrication. In this case, the heater and sensing material are integrated into a membrane (thin film) structure to minimize heat loss to the substrate and to heat the sensing material to a high temperature with lower power consumption. A heater-integrated gas sensor is manufactured by forming a heater and electrodes on an insulating layer, fabricating it into a membrane structure, and then forming a sensing material through synthesis, coating, etc., in the final step. In other words, the sensing material layer is located at the top of the gas sensor. Sensing materials are fabricated into nanostructures to increase the surface-to-volume ratio and maximize sensing performance; these nanostructures are formed by synthesizing nanowire or nanorod-shaped structures or by coating with dispersions of nanoparticles. However, sensing material layers formed in this manner have random shapes, leading to performance variations among devices within the wafer. Furthermore, the formation of sensing materials through synthesis typically carried out at high temperatures causes problems such as difficulty in forming them directly on metal electrodes or oxidation of the metal electrodes, and in the case of coating processes, issues such as stress being applied to the thin film or damage occurring during the application and drying of the solution may also occur. In this way, if the nanostructure formed on the top of the membrane is fabricated in an undesirable shape, it is difficult to remove and re-fabricate it, and a problem may arise where the specimen, which has already completed the membrane formation process, cannot be utilized and must be fabricated again from the beginning. The matters described above as background technology are intended only to enhance understanding of the background of the present invention and should not be construed as an acknowledgment that they constitute prior art already known to those skilled in the art. FIGS. 1 to 4 are flowcharts of a method for manufacturing a gas sensor according to an embodiment of the present invention. FIG. 5 is a gas sensor and a cross-sectional view according to an embodiment of the present invention. Hereinafter, specific details for solving the aforementioned objectives and problems will be explained in detail with reference to the attached drawings. Meanwhile, regarding the understanding of the present invention, if a detailed description of known technology in the same field does not help in understanding the core content of the invention, such description will be omitted. Furthermore, the technical concept of the present invention is not limited thereto and can be modified and implemented in various ways by those skilled in the art. Conventional gas sensors had a problem in that the sensing material was located at the top, making it difficult to coat the sensing material homogeneously on the upper surface of the electrode. Consequently, even gas sensors fabricated on the same wafer showed variations in sensing performance depending on their location on the wafer, and in some cases, these sensors failed to detect gas leakage. Therefore, gas sensors with a non-homogeneous coating of the sensing material on the upper surface of the electrode had to be discarded, resulting in cost losses. The gas sensor and the method for manufacturing the gas sensor according to the present invention have the effect of improving detection performance and deviations by placing the detection material at the bottom of other layers such as electrodes, insulating layers, and heaters, and minimizing cost losses even if the detection material is formed non-homogeneously. A method for manufacturing a gas sensor according to the present invention for achieving the above objective, with reference to FIGS. 1 and 2, comprises the steps of: forming a groove (110) on one side of the upper surface of a substrate (100) (S100); forming a first insulating layer (200) on the other side of the upper surface of the substrate (S200); forming a first sensing material (300) in the groove (S300); formin