A thin film hydrogen sensor, manufacturing method and working method

Abstract

The application discloses a thin film hydrogen sensor, a manufacturing method and a working method, which comprise a substrate, a hydrogen measuring thin film resistor sensitive to hydrogen, a temperature measuring thin film resistor sensitive to temperature and a heating thin film resistor arranged on the substrate; the temperature measuring thin film resistor and the heating thin film resistor are circular ring structures with the same center; a first gap is arranged on the temperature measuring thin film resistor to form a first temperature measuring terminal and a second temperature measuring terminal; a second gap is arranged on the heating thin film resistor to form a first heating terminal and a second heating terminal; the hydrogen measuring thin film resistor is arranged in parallel with the temperature measuring thin film resistor and the heating thin film resistor, and the hydrogen measuring thin film resistor is a parallel double helix structure. The thin film hydrogen sensor is relatively simple in structure, simple in manufacturing process, short in period, controllable in cost, high in stability and reliability, and can meet the cost requirement in the application of hydrogen fuel cell vehicles.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of sensor, and particularly relates to a thin film hydrogen sensor, a manufacturing method and a working method. BACKGROUND

[0002] Hydrogen fuel cell vehicles, as an application of hydrogen in the field of vehicles, are one of ideal solutions for new energy vehicles. However, hydrogen molecules are small and have strong permeability, and hydrogen is colorless and odorless, and has an ignition point of only 585 DEG C at normal temperature and pressure. Hydrogen content in the air is in the range of 4% to 74%, and can explode when meeting a fire source.

[0003] Solid-state palladium alloy thin film hydrogen measurement technology has specificity in detecting hydrogen, and can work normally in the presence or absence of oxygen, and has become a hot spot for application research of hydrogen leakage detection for vehicles. However, strong electromagnetic interference and large temperature changes occur when vehicles are running, which puts higher requirements on the anti-electromagnetic and temperature interference of palladium alloy thin film hydrogen sensors.

[0004] Chinese patent authorization announcement No. CN1947007B discloses a patent technology of a thin film gas sensor structure of an American H2SCAN company, and relates to a thin film hydrogen sensor based on a palladium-nickel alloy. The structure includes a MOS capacitor sensor for sensing small concentration hydrogen, a resistance sensor for sensing large concentration hydrogen, a nickel thin film temperature sensor and a thin film heating element. In the application of hydrogen fuel cell vehicles, hydrogen measurement focuses on the detection of large concentration hydrogen at the lower explosive limit, and the hydrogen sensor for sensing small concentration hydrogen has little significance in this application and will increase the cost.

[0005] The sensor contains two concentration range detection hydrogen elements. In terms of the application of hydrogen fuel cell vehicles only focusing on leakage detection, the long production cycle and high cost of the sensor will be caused, and in terms of the low-cost and high-reliability application requirements of vehicle hydrogen sensors, it is obviously not suitable. SUMMARY

[0006] The present application provides a thin film hydrogen sensor, a manufacturing method and a working method, which have simple structure, are easy to manufacture, have small influence of environmental temperature, and have strong anti-electromagnetic interference ability.

[0007] To solve the above technical problems, the present application adopts the following technical solutions: a thin film hydrogen sensor, comprising a substrate, the substrate is provided with a hydrogen sensing thin film resistor sensitive to hydrogen, a temperature sensing thin film resistor sensitive to temperature and a heating thin film resistor; the temperature sensing thin film resistor and the heating thin film resistor are circular ring structures with the same center, the temperature sensing thin film resistor is provided with a first gap to form a first temperature sensing terminal and a second temperature sensing terminal, the heating thin film resistor is provided with a second gap to form a first heating terminal and a second heating terminal, and the hydrogen sensing thin film resistor is arranged in the temperature sensing thin film resistor and the heating thin film resistor, and the hydrogen sensing thin film resistor is a parallel double helix structure.

[0008] The diameter of the heating thin film resistor is smaller than that of the temperature sensing thin film resistor, and the second gap and the first gap are adjacent and arranged in correspondence.

[0009] The center of the parallel double helix structure coincides with the center of the circular ring structure, the parallel double helix structure is formed by two groups of curves with the same radius difference and gradually changing around the center, the parallel double helix structure is short-circuited at the end point adjacent to the bottom die surface near the center, and the first hydrogen sensing terminal and the second hydrogen sensing terminal away from the center of the parallel double helix structure are adjacent to the second gap.

[0010] The substrate material is silicon, the hydrogen sensing thin film resistor is palladium-nickel alloy, the temperature sensing thin film resistor is platinum, and the heating thin film resistor is a metal material with stable physical and chemical properties, preferably nickel-chromium.

[0011] A manufacturing method of a thin film hydrogen sensor, comprising the following steps:

[0012] (1) determining the center of the substrate die surface, i.e. the center of the hydrogen sensing thin film resistor, the temperature sensing thin film resistor and the heating thin film resistor;

[0013] (2) installing the hydrogen sensing thin film resistor of the parallel double helix structure on the substrate, and short-circuiting the hydrogen sensing thin film resistor on the side close to the center point of the die surface;

[0014] (3) installing the heating thin film resistor on the silicon material substrate, so that the heating thin film resistor surrounds the hydrogen sensing thin film resistor outside;

[0015] (4) installing the temperature sensing thin film resistor on the silicon material substrate, so that the temperature sensing thin film resistor surrounds the heating thin film resistor outside;

[0016] (5) manufacturing a metal wire and a bonding pad on the silicon material substrate to form a thin film hydrogen sensor.

[0017] Step (1) is to form a pattern structure of the hydrogen sensing thin film resistor on the substrate die surface of the silicon material by photolithography technology, and then deposit the hydrogen sensing thin film resistor by heating evaporation or sputtering technology, and the parallel double helix structure can be obtained after stripping and cleaning.

[0018] Steps (2) and (3) are to deposit the heating thin film resistance and the temperature measuring thin film resistance respectively on the periphery of the hydrogen measuring thin film resistance by heating evaporation or sputtering technology.

[0019] A working method of a thin film hydrogen sensor, comprising the following steps:

[0020] A) The heating thin film resistance including the thin film hydrogen sensor is controlled by the peripheral circuit to adjust the voltage and the heating power;

[0021] B) The temperature measuring thin film resistance value in the thin film hydrogen sensor is collected by the peripheral circuit, and the heating resistance supply voltage in the above step A) is adjusted by a proper algorithm, so that the temperature of the thin film hydrogen sensor is stabilized in a certain range, and the influence of the environmental temperature change on the thin film resistance sensor is reduced;

[0022] C) The hydrogen concentration change is sensed by collecting the resistance value change of the hydrogen measuring thin film resistance in the thin film hydrogen sensor by the peripheral circuit, and the specific concentration value is obtained by the calibration fitting data curve of the resistance value change and the hydrogen concentration.

[0023] Compared with the prior art, the technical scheme has the following advantages:

[0024] The thin film hydrogen sensor of the present application has a simple and practical design, the hydrogen measuring thin film resistance has a parallel double helix structure, the heating thin film resistance and the temperature measuring thin film resistance surround the hydrogen measuring thin film resistance to form the geometric shape of the thin film hydrogen sensor. The hydrogen measuring thin film resistance has a parallel double helix structure, so that when the hydrogen measuring thin film resistance is interfered by the external electromagnetic interference, the current generated on the parallel two hydrogen measuring thin film resistances is equal in size and opposite in direction, the induced magnetic field generated by the current itself is also equal in size and opposite in direction, and the induced magnetic field can be cancelled out, thereby enhancing the anti-electromagnetic interference capability and effectively eliminating the signal interference introduced by the system itself and the external environment.

[0025] Meanwhile, the heating thin film resistance is in the inner ring, the temperature measuring thin film resistance is in the outer ring, the hydrogen measuring thin film resistance is placed in the center of the temperature field through the parallel double helix structure, and the heating thin film resistance and the temperature measuring thin film resistance surround the center point of the bottom die. The heating resistance and the temperature measuring resistance form a temperature control unit to provide a relatively constant temperature for the system, and the isotropic annular structure is conducive to the relatively stable temperature field of the hydrogen measuring thin film resistance located in the center of the annular structure, thereby reducing the disturbance of the temperature fluctuation to the hydrogen measuring resistance and enhancing the stability of the output signal of the hydrogen sensor.

[0026] The thin film hydrogen sensor of the present application has a relatively simple structure, a simple manufacturing process, a short cycle, controllable cost, strong stability and reliability, and can meet the cost requirements in the application of hydrogen fuel cell vehicles. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1is a structural schematic diagram of the present application. DETAILED DESCRIPTION

[0028] As Figure 1 shown, a thin film hydrogen sensor of the present application includes a substrate 10, the substrate 10 is provided with a hydrogen-sensing thin film resistor 1, a temperature-sensing thin film resistor 3 and a heating thin film resistor 2 on the die surface; the temperature-sensing thin film resistor 3 and the heating thin film resistor 2 are circular ring structures with the same center, the temperature-sensing thin film resistor 3 is provided with a first gap to form a first temperature-sensing terminal 3a and a second temperature-sensing terminal 3b, the heating thin film resistor 2 is provided with a second gap to form a first heating terminal 2a and a second heating terminal 2b, the hydrogen-sensing thin film resistor 1 is arranged between the temperature-sensing thin film resistor 3 and the heating thin film resistor 2, and the hydrogen-sensing thin film resistor 1 is a parallel double helix structure.

[0029] The diameter of the heating thin film resistor 2 is smaller than that of the temperature-sensing thin film resistor 3, the second gap and the first gap are adjacent and arranged in correspondence.

[0030] The center of the parallel double helix structure coincides with the center of the circular ring structure, the parallel double helix structure is formed by two groups of curves with the same radius difference and gradually changing around the center 0, the parallel double helix structure is short-circuited at the end point adjacent to the die surface near the center 0, and the first hydrogen-sensing terminal 1a and the second hydrogen-sensing terminal 1b of the parallel double helix structure away from the center 0 are adjacent to the second gap.

[0031] The substrate 10 is made of silicon, the hydrogen-sensing thin film resistor 1 is made of palladium-nickel alloy, the temperature-sensing thin film resistor 3 is made of platinum, and the heating thin film resistor 2 is made of a metal material with stable physical and chemical properties, preferably nickel-chromium.

[0032] A manufacturing method of a thin film hydrogen sensor, comprising the following steps:

[0033] (1) Determine the center of the die surface of the substrate 10, that is, the center 0 of the hydrogen-sensing thin film resistor 1, the temperature-sensing thin film resistor 3 and the heating thin film resistor 2;

[0034] (2) Clean the silicon wafer substrate 10 to remove surface impurities; use a photolithography process to manufacture the pattern structure of the hydrogen-sensing thin film resistor 1 parallel double helix, and form a photoresist mask. Use a thermal evaporation process to deposit a palladium-nickel alloy thin film, the thickness of the thin film is 50-150 nm, and use a lift-off process to strip and clean the hydrogen-sensing thin film resistor 1 with a parallel double helix structure.

[0035] (3) Use a photolithography process to manufacture a photoresist mask pattern of the heating thin film resistor 2. Deposit a nickel-chromium thin film by a thermal evaporation process, the thickness of the thin film is 300-500 nm, and then strip and clean to manufacture the heating thin film resistor 2. Use a photolithography process to manufacture a photoresist mask pattern of the temperature-sensing thin film resistor 3.

[0036] (4) Depositing platinum thin film by thermal evaporation process, the film thickness is 50nm-150nm, then stripping cleaning to form platinum thin film temperature measuring resistance.

[0037] (5) Making photoresist mask pattern of metal connection and bonding pad by photoetching process. Depositing gold thin film by thermal evaporation process, the film thickness is 400nm-700nm, then stripping cleaning to form metal connection and pad. Making thin film hydrogen sensor by scribing machine.

[0038] A working method of a thin film hydrogen sensor, comprising the following steps:

[0039] A) Adjusting the voltage control heating power of the heating thin film resistance 2 including the thin film hydrogen sensor by the peripheral circuit;

[0040] B) Collecting the value of the temperature measuring thin film resistance 3 inside the thin film hydrogen sensor by the peripheral circuit, and adjusting the power supply voltage of the heating resistance in the above step A) by a proper algorithm, so that the temperature of the thin film hydrogen sensor is stabilized in a certain range, and the influence of the environmental temperature change on the thin film resistance sensor is reduced;

[0041] C) Collecting the resistance value change of the hydrogen measuring thin film resistance 1 in the thin film hydrogen sensor to sense the hydrogen concentration change, and obtaining the specific concentration value of the hydrogen concentration through the calibration fitting data curve.

[0042] The application applies the hydrogen measuring, heating, temperature measuring thin film resistance 3 to surround the center point of the substrate 10 module surface in a triple ring structure, so that the hydrogen measuring thin film resistance 1 is in a relatively stable and consistent temperature field. In the experiment, when the temperature control temperature of the heating thin film resistance 2 and the temperature measuring thin film resistance 3 is 140 degrees, and the peripheral environmental temperature is 25 degrees, it can be known through ANSYS software analysis that compared with other thin film sensors, the hydrogen measuring thin film resistance 1 of the application is in a relatively stable temperature field.

[0043] If the temperature control temperature is 140 degrees, and the peripheral environmental temperature is minus 40 degrees, it can be known through ANSYS software analysis that compared with other thin film sensors, the hydrogen measuring thin film resistance 1 of the application is still in a relatively stable temperature field.

[0044] The embodiment is not limited in shape, material, structure and the like of the application in any form, and any simple modification, equivalent change and modification of the above embodiment according to the technical essence of the application are all within the protection scope of the technical solution of the application.

Claims

1. A method of fabricating a thin film hydrogen sensor, comprising: The thin film hydrogen sensor comprises a substrate, a hydrogen-sensing thin film resistor, a temperature-sensing thin film resistor and a heating thin film resistor on the substrate; the temperature-sensing thin film resistor and the heating thin film resistor are in a circular ring structure with the same center; the temperature-sensing thin film resistor is provided with a first gap to form a first temperature-sensing terminal and a second temperature-sensing terminal; the heating thin film resistor is provided with a second gap to form a first heating terminal and a second heating terminal; the hydrogen-sensing thin film resistor is in a parallel double helix structure between the temperature-sensing thin film resistor and the heating thin film resistor; ​ The diameter of the heating thin film resistor is smaller than that of the temperature-sensing thin film resistor; the second gap and the first gap are adjacent and arranged in correspondence with each other; The center of the parallel double helix structure coincides with the center of the circular ring structure; the parallel double helix structure is formed by two groups of curves with the same radius difference and gradually changing around the center; the parallel double helix structure is short-circuited at the end point near the center of the bottom die surface; the first hydrogen-sensing terminal and the second hydrogen-sensing terminal of the parallel double helix structure are adjacent to the second gap; The substrate is made of silicon; the hydrogen-sensing thin film resistor is made of palladium-nickel alloy; the temperature-sensing thin film resistor is made of platinum; and the heating thin film resistor is made of nickel or chromium with stable physical and chemical properties; The manufacturing method of the thin film hydrogen sensor comprises the following steps: (1) determining the center of the substrate die surface, i.e. the center of the hydrogen-sensing thin film resistor, the temperature-sensing thin film resistor and the heating thin film resistor; (2) installing the hydrogen-sensing thin film resistor in the parallel double helix structure on the substrate; the hydrogen-sensing thin film resistor is short-circuited on the side close to the center point of the die surface; (3) installing the heating thin film resistor on the silicon material substrate so that the heating thin film resistor surrounds the hydrogen-sensing thin film resistor outside; (4) installing the temperature-sensing thin film resistor on the silicon material substrate so that the temperature-sensing thin film resistor surrounds the heating thin film resistor outside; (5) manufacturing the thin film hydrogen sensor by making metal wires and bonding pads on the silicon material substrate.

2. The method of claim 1, wherein: Step (1) is to form a pattern structure of the hydrogen-sensing thin film resistor on the substrate die surface of the silicon material by photolithography technology, and then deposit the hydrogen-sensing thin film resistor by heating evaporation or sputtering technology, and the parallel double helix structure can be obtained after stripping and cleaning.

3. The method of claim 2, wherein: Steps (2) and (3) are to deposit the heating thin film resistor and the temperature-sensing thin film resistor outside the hydrogen-sensing thin film resistor by heating evaporation or sputtering technology.

4. A method of operating a thin film hydrogen sensor made according to the method of claim 3, characterized by: The method comprises the following steps: A) adjusting the voltage control heating power of the heating thin film resistor of the thin film hydrogen sensor through the peripheral circuit; B) collecting the temperature-sensing thin film resistor value inside the thin film hydrogen sensor through the peripheral circuit, and adjusting the heating thin film resistor power supply voltage in step A) through a suitable algorithm, so that the temperature of the thin film hydrogen sensor is stable within a certain range, and the influence of environmental temperature change on the thin film resistor sensor is reduced; C) collecting the hydrogen-sensing thin film resistor resistance value change of the thin film hydrogen sensor through the peripheral circuit to sense the hydrogen concentration change, and the specific concentration value is obtained through the calibration fitting data curve of the resistance value change and the hydrogen concentration.

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