KR100895071B1 - Hydrogen sensor using resistance temperature detector and fabricating method thereof - Google Patents

Abstract

The present invention relates to a hydrogen leak detection sensor using a resistance thermometer and a manufacturing method thereof, comprising: a contact combustion type hydrogen leak detection sensor for detecting hydrogen gas; An SOI substrate; Silicon oxide films formed on both upper and lower surfaces of the SOI substrate; A first adhesive layer formed of Ti on the silicon oxide film formed on the top surface of the SOI substrate; A coil-shaped platinum heater formed on an upper surface of the first adhesive layer; A first alumina insulating film formed on the platinum heater so as to completely cover the platinum heater; A second adhesive layer formed of Ti on an upper surface of the first alumina insulating film; A resistance thermometer formed of platinum on an upper surface of the second adhesive layer; A second alumina insulating film formed on an upper surface of the RTD; A third adhesive layer formed of Ti on an upper surface of the second alumina insulating film; A platinum catalyst layer formed on an upper surface of the third adhesive layer; Provided is a hydrogen leakage detection sensor using a RTD including a silicon oxide film formed on a bottom surface of the SOI substrate and a back etching portion formed by dry etching of the SOI substrate, and a method of manufacturing the same.

Accordingly, the present invention can be used to measure the concentration of hydrogen stably without affecting damage due to deterioration of the heater and a large change in resistance over time by using the RTD as a heater, and also MEMS (Micro Electro Mechanical Systems) technology This makes it possible to mass-produce at a low price, and to enable low power operation and miniaturization.

Hydrogen sensor, platinum, MEMS, SOI, catalytic combustion, catalyst, resistance thermometer

Description

Hydrogen leak detection sensor using RTD and its manufacturing method {HYDROGEN SENSOR USING RESISTANCE TEMPERATURE DETECTOR AND FABRICATING METHOD THEREOF}

The present invention relates to a hydrogen leakage detection sensor using a RTD and a method for manufacturing the same. More specifically, the RTD can be measured without using a RTD without affecting damage caused by deterioration of a heater or large changes in resistance over time. In addition, the present invention relates to a hydrogen leak detection sensor using a resistance thermometer and a method for manufacturing the same, which can be miniaturized through a MEMS process and can be made highly sensitive and low power.

In general, the outlook for fossil fuels is not bright. In 2003, British refinery British Petroleum (BP) estimated that fossil fuel reserves remained 40 years of crude oil, 62 years of natural gas and 216 years of coal. But with the advent of big energy consumers like China and India, it is expected to be shorter. Therefore, research to replace fossil fuels with hydrogen energy is being conducted worldwide.

Hydrogen energy is receiving attention as an alternative energy source for the energy supply and demand problem.

Hydrogen is being researched worldwide as a clean energy source, and is currently being used in fuel cells and internal combustion engines. It is expected that consumption will increase in the fields of fuel cell vehicles and power generation power generation in the coming years.

However, since hydrogen has a high flash point and explodes when it is above a certain concentration, the need for a hydrogen sensor that can detect the leakage of hydrogen in the process of dealing with it is important.

For example, fuel cells generate electricity through the chemical reaction between hydrogen and oxygen, but the explosion range of hydrogen is 4 ~ 75%, and the ignition is possible even with energy of 0.02mJ in the atmosphere. Is a very big problem, and the diffusion coefficient is so high that it can easily diffuse through most materials, making it difficult to trap in a specific container. In some cases, it can detect hydrogen concentrations of about 1000 ppm to 4%. Detecting sensors are required.

Currently disclosed hydrogen leakage detection sensor is manufactured by using semiconductor manufacturing technology such as MEMS (Micro Electro Mechanical Systems) and MISFET (Metal Insulator Semiconductor FET) using thick film or thin film material, so it has low power consumption and easy to miniaturize. Although there is a defect in the resistance change and damage caused by the deterioration and crack of the heater in a long time use, that is, the heater is a thin platinum film of the fine wiring and the film thickness is wide instead of thin so that the concentration of current in a certain part Phenomena tend to occur, causing problems such as high temperature oxidation and cracks due to local heat generation, which in turn causes a resistance change and damage of the heater, thereby shortening the life of the sensor.

The present invention has been made in view of the above-mentioned problems in the prior art, and has been created to solve this problem. The hydrogen leakage detection sensor, in particular, a contact combustion type hydrogen sensor, can be miniaturized, and the driving reaction power can be lowered. The main purpose is to extend the life of the sensor by preventing the deterioration and damage of the heater by using the atmosphere and the platinum group catalyst, but by separately configuring the heater and the RTD in the detection unit, and to provide a more sensitive hydrogen leakage detection sensor and its manufacturing method. have.

The present invention provides a contact combustion type hydrogen leakage detection sensor for detecting hydrogen gas in order to achieve the above technical problem; An SOI substrate; Silicon oxide films formed on both upper and lower surfaces of the SOI substrate; A first adhesive layer formed of Ti on the silicon oxide film formed on the top surface of the SOI substrate; A coil-shaped platinum heater formed on an upper surface of the first adhesive layer; A first alumina insulating film formed on the platinum heater so as to completely cover the platinum heater; A second adhesive layer formed of Ti on an upper surface of the first alumina insulating film; A resistance thermometer formed of platinum on an upper surface of the second adhesive layer; A second alumina insulating film formed on an upper surface of the RTD; A third adhesive layer formed of Ti on an upper surface of the second alumina insulating film; A platinum catalyst layer formed on an upper surface of the third adhesive layer; Provided is a hydrogen leakage detection sensor using a resistance thermometer including a silicon oxide film formed on the bottom surface of the SOI substrate and a back etching portion formed by dry etching the SOI substrate.

At this time, one detector element and three compensation elements are formed in the platinum heater and the RTD so as to be symmetrical, and a total of 16 pads are formed in each of the two elements.

In addition, the silicon oxide film is formed to a thickness of 4000-6000Å, the first, 2, 3 adhesive layer is formed to a thickness of 100-300Å, the platinum heater is formed to a thickness of 1000-3000Å, the first, The alumina insulating film is formed to a thickness of 2500-5000Å, the RTD is formed to a thickness of 500-1500Å, and the platinum catalyst layer is characterized in that it is formed to a thickness of 200-700Å.

In addition, the present invention, in order to achieve the above technical problem, a method for manufacturing a hydrogen leakage detection sensor; A first step of forming a silicon oxide film having a thickness of 4000-6000Å by depositing SiO ₂ on both sides of the SOI substrate by dry oxidation on top and bottom thereof; A second step of forming a first adhesive layer with a thickness of 100-300 GPa over Ti formed on the top surface of the SOI substrate among the silicon oxide films formed in the first step; A third step of depositing a platinum heater on the first adhesive layer formed in the second step and patterning the coil in a coil form using a lift-off method; A fourth step of depositing and patterning a first alumina insulating film by sputtering Al ₂ O ₃ to a thickness of 2500-5000 kPa so that the platinum heater patterned in the third step is buried; A fifth step of forming a second adhesive layer with a thickness of 100-300 GPa on Ti on the alumina insulating film patterned in the fourth step; A sixth step of depositing a resistance thermometer with a thickness of 500 to 1500 kW on a second adhesive layer formed in the fifth step, and patterning the same as the platinum heater but staggering from each other; A seventh step of depositing and patterning a second alumina insulating film having a thickness of 2500-5000 kV over the RTD formed in the sixth step; An eighth step of forming a third adhesive layer with a thickness of 100-300 GPa over Ti on the second alumina insulating film formed in the seventh step; A ninth step of forming a platinum catalyst layer on the third adhesive layer formed in the eighth step to a thickness of 200-700 Å and then patterning by a lift-off method; After the ninth step, there is also provided a method of manufacturing a hydrogen leakage detection sensor using a RTD comprising a tenth step of etching and etching the silicon oxide film forming the back surface of the hydrogen sensor and the SOI substrate.

The present invention can stably measure the concentration of hydrogen without damage caused by deterioration of the heater and large time-varying change in resistance by using the RTD together with the heater. It is possible to drive low power and miniaturization.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment according to the present invention.

1 is a cross-sectional view showing a basic configuration of a contact combustion type hydrogen leakage detection sensor according to the present invention, Figure 2 is a plan view of a contact combustion type hydrogen leakage detection sensor according to the present invention, Figure 3 is a contact combustion type according to the present invention It is a process chart which shows the manufacturing process of a hydrogen leakage detection sensor.

First, the contact combustion type hydrogen leakage detection sensor according to the present invention is provided with a heater and a RTD separately in a detection unit so that the concentration of hydrogen can be measured by the RTD without the influence of a heater that is easily damaged and has a large change over time. .

To this end, the present invention uses a silicon on insulator (SOI) wafer as a substrate, forms an heater after applying an initial oxide film on the substrate, and arranges an insulating film between the heater and the RTD. It is preferable to use alumina, aluminum nitride, or the like because it should be excellent in thermal conductivity while blocking electrical interference between the heater and the RTD.

The hydrogen sensor may be configured by forming an RTD in a coil shape using platinum and then again placing an insulating film, forming a platinum catalyst film thereon, and finally dry etching the rear surface of the sensor.

In an exemplary embodiment of the present invention, as shown in FIG. 1, an SOI substrate 100 is provided, and an insulator (SiO ₂ ) is coated on both sides of the SOI substrate 100 to form a silicon oxide film 200. do.

In this case, the silicon oxide film 200 may serve to prevent the heat from the heater or the catalyst from being dispersed outside as well as the support of the hydrogen sensor of the present invention.

In addition, a first adhesive layer 300 is formed using Ti to form the platinum heater 400, and the first adhesive layer 300 increases the adhesion between the silicon oxide film 200 and the platinum heater 400. It is to give.

Here, Ti and Pt are sequentially formed by sputtering, and then the platinum heater 400 is patterned by a lift-off method, and the first alumina insulating film 500 is used to block electrical interference of the platinum heater 400. It is preferable to completely cover the platinum heater 400 using the).

In addition, the platinum heater 400 is preferably formed in the form of a coil.

At this time, the thickness of the first alumina insulating film 500 should have a sufficient thickness so as not to short the catalyst and the heater during the process, but if too thick, the sensitivity of the sensor is lowered depending on the process equipment and environment, but the thickness of the heater About 150% is preferable.

Subsequently, a resistance thermometer 610 is formed, and the resistance thermometer 610 is preferably formed of platinum, and the first alumina insulating film 500 includes a second adhesive layer 600 containing Ti as a main component to improve adhesion. It is preferred to be deposited above.

Then, the second alumina insulating film 630 is formed again on the RTD 610.

Subsequently, the catalyst layer is formed, and preferably, the platinum catalyst layer 700 may be formed. In this case, the third adhesive layer 630 may be formed of Ti to form a space between the platinum catalyst layer 700 and the second alumina insulating film 620. It is more preferable to increase the adhesive force of the.

Here, the platinum catalyst layer 700 may be formed only in an area corresponding to one of four elements of the hydrogen sensor, and thus may be divided into a detection element and a compensation element.

Finally, the hydrogen leakage detection sensor of the present invention is completed by forming the back etching unit 800 by etching the back side of the SOI substrate 100 by dry etching to improve thermal efficiency and distribution of the sensor.

For example, Figure 2 is a plan view of the contact combustion hydrogen leakage detection sensor of the present invention, since the sensor signal is output by using a bridge circuit in an external system, the sensor is symmetrical to each other and one detection element (DE) and three It may be composed of a compensation element (CE).

They are open to each other and can be composed of two pads (P) in each element, that is, eight pads (P) for each of the heater and the resistance thermometer. To minimize interference with each other, and in the case of RTD, the Wheatstone bridge circuit can be used to obtain an electrical signal for hydrogen concentration. In the case of the heater, each pad (P) is exposed. Active circuit application is possible.

Hereinafter, a method of manufacturing a hydrogen leak detection sensor using the RTD according to the present invention will be described in more detail with reference to the following.

As shown in FIG. 3, as described above, in the state in which the SOI substrate 100 is provided, the silicon oxide film 200 is deposited to a thickness of 4000-6000 μs by depositing SiO ₂ on the upper and lower surfaces thereof by a dry oxidation method. The first adhesive layer 300 is formed of Ti to form the platinum heater 400 by using a lift-off method, and then the platinum heater 400 is deposited.

In this case, the thickness of the first adhesive layer 300 is preferably 100-300 kPa, and the platinum heater 400 is deposited on the first adhesive layer 300 by using an evaporator at an thickness of 1000-3000 kPa. , The platinum heater 400 is patterned in the form of a coil by a lift-off method.

Then, in order to prevent electrical interference of the platinum heater 400 by depositing the platinum heater 400 in the first alumina insulation film 500, there is the patterning by a lift-off method in this case Al ₂ O ₃ with a thickness of 2500-5000Å It is preferable to deposit by sputtering.

In addition, the patterning of the first alumina insulating film 500 is preferably such that only the pad (P) of the platinum heater 400 is exposed to the outside.

In order to form the RTD 610, a second adhesive layer 600 is formed on the upper surface of the first alumina insulating film 500 at the same thickness as that of the first adhesive layer 300, and then the RTD is measured. It is preferable to form 610.

At this time, the RTD 610 is preferably used platinum, it is also preferably patterned in the form of a coil having the same shape as the platinum heater 400.

In this way, the RTD 610 is formed, and the second alumina insulating film 620 and the third adhesive layer 630 made of Ti are deposited thereon.

Here, the second alumina insulating film 620 may also be formed by using a lift-off method to cover the RTD 610 like the first alumina insulating film 500.

Subsequently, platinum is also deposited to form a catalyst layer 700 to form a catalyst layer 200-700 다음 and then patterned to form a catalyst film. In this case, the platinum catalyst layer 700 is deposited by an evaporator to be deposited to increase adhesion, and is described above. As described above, the third adhesive layer 630 may be formed in advance on the second alumina insulating film 620 to have the same thickness as the first adhesive layer 300 using Ti, and the patterning of the platinum catalyst layer 700 may also be performed. It is preferable to carry out using a lift-off method.

Lastly, after the platinum catalyst layer 700 is formed, the backside etching of the hydrogen sensor is particularly preferably performed by dry etching to be effective for heat distribution and efficiency.

The structure of the hydrogen sensor manufactured in this way can be easily implemented, and mass production is also possible, which has the advantage of significantly lowering the cost.

1 is a cross-sectional view showing the basic configuration of the contact combustion hydrogen leakage detection sensor according to the present invention,

2 is an exemplary plan view of a contact combustion hydrogen leak detection sensor according to the present invention;

Figure 3 is a process diagram showing a method of manufacturing a contact combustion hydrogen leakage detection sensor according to the present invention.

♧ description of the symbols for the main parts of the drawing ♧

Silicon On Insulator (SOI) 200 ... Silicon Oxide

300 .... First adhesive layer 400 .... Platinum heater

500 .... first alumina insulating film 600 ... second adhesive layer

610 .... temperature resistance resistor 620 .... second alumina insulating film

630 ... 3rd adhesive layer 700 ... platinum catalyst layer

800 .... back etching

Claims (4)

A contact combustion type hydrogen leak detection sensor for detecting hydrogen gas; An SOI substrate; Silicon oxide films formed on both upper and lower surfaces of the SOI substrate; A first adhesive layer formed of Ti on the silicon oxide film formed on the top surface of the SOI substrate; A coil-shaped platinum heater formed on an upper surface of the first adhesive layer; A first alumina insulating film formed on the platinum heater so as to completely cover the platinum heater; A second adhesive layer formed of Ti on an upper surface of the first alumina insulating film; A resistance thermometer formed of platinum on an upper surface of the second adhesive layer; A second alumina insulating film formed on an upper surface of the RTD; A third adhesive layer formed of Ti on an upper surface of the second alumina insulating film; A platinum catalyst layer formed on an upper surface of the third adhesive layer; And a silicon oxide film formed on the bottom surface of the SOI substrate and a back etching portion formed by dry etching the SOI substrate. The method according to claim 1; The platinum heater and the RTD are formed so that one detection element and three compensation elements are symmetrical, and a total of 16 pads are formed in each of the two elements, and the hydrogen leakage detection sensor using the RTD. The method according to claim 1 or 2; The silicon oxide film is formed to a thickness of 4000-6000Å, The first, second, third adhesive layer is formed to a thickness of 100-300Å, The platinum heater is formed to a thickness of 1000-3000Å, The first and second alumina insulating film is formed to a thickness of 2500-5000Å, The RTD is formed to a thickness of 500-1500Å, The platinum catalyst layer is hydrogen leakage detection sensor using a resistance thermometer, characterized in that formed to a thickness of 200-700Å. A method of manufacturing a hydrogen leak detection sensor; A first step of forming a silicon oxide film having a thickness of 4000-6000Å by depositing SiO ₂ on both sides of the SOI substrate by dry oxidation on top and bottom thereof; A second step of forming a first adhesive layer with a thickness of 100-300 GPa over Ti formed on the top surface of the SOI substrate among the silicon oxide films formed in the first step; A third step of depositing a platinum heater on the first adhesive layer formed in the second step and patterning the coil in a coil form using a lift-off method; A fourth step of depositing and patterning a first alumina insulating film by sputtering Al ₂ O ₃ to a thickness of 2500-5000 kPa so that the platinum heater patterned in the third step is buried; A fifth step of forming a second adhesive layer with a thickness of 100-300 GPa on Ti on the alumina insulating film patterned in the fourth step; A sixth step of depositing a resistance thermometer with a platinum material on the second adhesive layer formed in the fifth step, and patterning the same as the platinum heater but staggering each other; A seventh step of depositing and patterning a second alumina insulating film having a thickness of 2500-5000 kV over the RTD formed in the sixth step; An eighth step of forming a third adhesive layer with a thickness of 100-300 GPa over Ti on the second alumina insulating film formed in the seventh step; A ninth step of forming a platinum catalyst layer on the third adhesive layer formed in the eighth step to a thickness of 200-700 Å and then patterning by a lift-off method; And a tenth step of dry etching the silicon oxide film and the SOI substrate which form the back surface of the hydrogen sensor after the ninth step, wherein the hydrogen leakage detection sensor is manufactured using the RTD.

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