Magnesium-based thin film hydrogen sensor as well as preparation method and application thereof

Abstract

The invention relates to the technical field of sensors, and particularly discloses a magnesium-based thin film hydrogen sensor as well as a preparation method and application thereof. The magnesium-based thin film hydrogen sensor comprises an insulating layer, and a first hydrogen sensitive resistor, a second hydrogen sensitive resistor, a first reference resistor and a second reference resistor which are arranged on the insulating layer and form a Wheatstone bridge structure; each of the first hydrogen sensitive resistor and the second hydrogen sensitive resistor comprises a hydrogen sensitive layer; each of the first reference resistor and the second reference resistor comprises a hydrogen sensitive layer and a barrier layer covering the hydrogen sensitive layer, the electrical property change of the hydrogen sensitive layer is related to the concentration of hydrogen on the surface of the hydrogen sensitive layer, and the barrier layer prevents the hydrogen sensitive layer from being in contact with hydrogen. The magnesium-based thin film hydrogen sensor has the advantages of being low in working temperature, high in sensitivity and high in hydrogen selectivity.

Description

Technical Field

[0001] The present application relates to the field of sensor technology, and in particular to a magnesium-based thin film hydrogen sensor and a preparation method and application thereof. Background Art

[0002] With the development of hydrogen production technology, hydrogen storage technology and hydrogen fuel cells, the use of hydrogen energy has become a hot topic. Hydrogen is colorless, odorless, tasteless, and has a wide range of flammability. During the storage and use of hydrogen, the interaction between hydrogen and the materials it contacts causes hydrogen embrittlement and leads to failure of parts or mechanisms, causing hydrogen overflow or leakage, causing fire and even explosion hazards. Therefore, the study of high-performance hydrogen sensors is of great significance for early warning of hydrogen leakage, energy storage detection and the development of hydrogen energy.

[0003] Hydrogen sensors in the prior art mainly include catalytic combustion hydrogen sensors, electrochemical hydrogen sensors, optical fiber hydrogen sensors, work function hydrogen sensors and resistance hydrogen sensors. Although the catalytic combustion hydrogen sensor has stable performance and a wide operating temperature range, its power consumption is very high; the electrochemical hydrogen sensor has the advantages of low operating temperature and high sensitivity, but has the disadvantages of difficult packaging, easy corrosion, and easy leakage; the optical fiber hydrogen sensor has high requirements for the preparation process, complex structure, high cost, and relatively complex signal monitoring; although the work function hydrogen sensor has high sensitivity, it has a small test range, is difficult to manufacture, and has a high operating temperature and serious response lag; the resistance hydrogen sensor uses the resistance change generated by the reaction of hydrogen-sensitive materials with hydrogen to monitor the hydrogen concentration. According to the resistivity change mechanism and the difference in hydrogen-sensitive materials, it can be divided into metal resistance type and metal oxide semiconductor resistance type hydrogen sensors. Commonly used hydrogen-sensitive materials include zinc oxide, tin oxide, and tungsten oxide, but these oxide hydrogen-sensitive materials have the disadvantages of poor selectivity and high operating temperature; if metal hydrogen-sensitive material palladium is selected as the metal hydrogen-sensitive material, although it has the advantages of high selectivity and high sensitivity, it has hydrogen embrittlement, and the price of palladium is very expensive. Therefore, the existing technology needs to be improved. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the purpose of the present application is to provide a magnesium-based thin film hydrogen sensor and its preparation method and application, aiming to solve the problems of low operating temperature, low sensitivity, complex preparation process and high cost of existing hydrogen sensors.

[0005] The technical solution of this application is as follows: In a first aspect of the present application, a magnesium-based thin film hydrogen sensor is provided, comprising an insulating layer and a first hydrogen-sensitive resistor, a second hydrogen-sensitive resistor, a first reference resistor and a second reference resistor arranged on the insulating layer, wherein the first hydrogen-sensitive resistor, the second hydrogen-sensitive resistor, the first reference resistor and the second reference resistor constitute a Wheatstone bridge structure; wherein one end of the first hydrogen-sensitive resistor is connected to the first reference resistor through a first electrode, and the other end is connected to the second reference resistor through a second electrode, one end of the second hydrogen-sensitive resistor is connected to the second reference resistor through a third electrode, and the other end is connected to the first reference resistor through a fourth electrode; the first hydrogen-sensitive resistor and the second hydrogen-sensitive resistor both comprise a hydrogen-sensitive layer; the first reference resistor and the second reference resistor both comprise a hydrogen-sensitive layer and a barrier layer covering the hydrogen-sensitive layer; a change in the electrical properties of the hydrogen-sensitive layer is related to the concentration of hydrogen on the surface of the hydrogen-sensitive layer, and the barrier layer blocks the hydrogen-sensitive layer from contacting with hydrogen.

[0006] Preferably, the hydrogen sensitive layer has a comb-like structure, which includes 20-80 comb teeth, the comb teeth are evenly distributed, and the gap between two adjacent comb teeth is 50-200 μm; the comb teeth include two side teeth and a middle tooth located between the two side teeth, the width of the side teeth is 300-550 μm, and the width of the middle teeth is 50-200 μm.

[0007] Preferably, the hydrogen sensitive layer includes a magnesium-based film layer, the thickness of the magnesium-based film layer is 30-150nm; the magnesium-based film layer includes a pure magnesium film or a magnesium alloy, the magnesium alloy is selected from magnesium-palladium alloy, magnesium-iron alloy, magnesium-rhenium alloy, and the mass content of magnesium in the magnesium alloy is greater than or equal to 50%.

[0008] The hydrogen sensitive layer also includes a chromium thin film layer and a palladium thin film layer, the chromium thin film layer is arranged on the insulating layer, the magnesium-based thin film layer is arranged on the chromium thin film layer, and the palladium thin film layer is arranged on the magnesium-based thin film layer; the thickness of the chromium thin film layer is 3-10nm, and the thickness of the palladium thin film layer is 5-10nm.

[0009] Preferably, the barrier layer has a thickness of 200-300 nm, and the barrier layer comprises silicon carbide or silicon dioxide.

[0010] Preferably, the first electrode, the second electrode, the third electrode and the fourth electrode each include a chromium intermediate layer and a gold electrode layer disposed on the chromium intermediate layer, the chromium intermediate layer has a thickness of 3-10 nm, and the gold electrode layer has a thickness of 150-300 nm.

[0011] Preferably, the thickness of the insulating layer is 300-500 nm, and the insulating layer is made of silicon dioxide by a thermal oxidation process.

[0012] Preferably, the magnesium-based thin film hydrogen sensor comprises a substrate layer, the insulating layer is arranged on the substrate layer, and the substrate layer is a silicon substrate layer.

[0013] In a second aspect of the present application, a method for preparing the magnesium-based thin film hydrogen sensor of the first aspect of the present application is provided, comprising the steps of: A hydrogen sensitive layer is prepared on the insulating layer by magnetron sputtering to obtain a first hydrogen sensitive resistor, a second hydrogen sensitive resistor, a first reference resistor precursor and a second reference resistor precursor; a first electrode, a second electrode, a third electrode and a fourth electrode are prepared on the insulating layer by magnetron sputtering or evaporation; a blocking layer is prepared on the hydrogen sensitive layer of the first reference resistor precursor and the hydrogen sensitive layer of the second reference resistor precursor by magnetron sputtering or chemical vapor deposition.

[0014] The third aspect of the present application provides an application of the magnesium-based thin film hydrogen sensor of the first aspect of the present application in detecting hydrogen concentration.

[0015] Beneficial effects of this application: The magnesium-based thin film hydrogen sensor of the present application includes a Wheatstone bridge structure composed of a first hydrogen-sensitive resistor, a second hydrogen-sensitive resistor, a first reference resistor and a second reference resistor. When the magnesium-based thin film hydrogen sensor is exposed to hydrogen, the electrical properties of the first hydrogen-sensitive resistor and the second hydrogen-sensitive resistor change after contacting with hydrogen (conductivity changes or resistance changes). The first reference resistor and the second reference resistor cannot contact with hydrogen due to the effect of the barrier layer. Based on this, the concentration of hydrogen can be determined by detecting the output voltage change of the magnesium-based thin film hydrogen sensor. In the magnesium-based thin film hydrogen sensor of the present application, only hydrogen can affect the electrical properties of the first hydrogen-sensitive resistor and the second hydrogen-sensitive resistor, and by constructing a Wheatstone bridge structure in the magnesium-based thin film hydrogen sensor, the subtle changes in the electrical properties of the first hydrogen-sensitive resistor and the second hydrogen-sensitive resistor can be measured, thereby improving the sensitivity and accuracy of the magnesium-based thin film hydrogen sensor in detecting hydrogen concentration. At the same time, the magnesium-based thin film hydrogen sensor of the present application has low operating power, low operating temperature and simple preparation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for describing the embodiments are briefly introduced below.

[0017] Figure 1 A top view of a magnesium-based thin film hydrogen sensor provided in an embodiment of the present application; Figure 2 A side view of a magnesium-based thin film hydrogen sensor provided in an embodiment of the present application; Figure 3 A top view of another magnesium-based thin film hydrogen sensor provided in an embodiment of the present application; Figure 4 A schematic diagram of the circuit connection of the magnesium-based thin film hydrogen sensor provided in an embodiment of the present application; Figure 5 A schematic diagram of the structure of a first hydrogen sensitive resistor provided in an embodiment of the present application; Figure 6 A hydrogen sensitivity test diagram of a resistive hydrogen sensor provided in an embodiment of the present application; Figure 7 This is a hydrogen sensitivity test diagram of the magnesium-based thin film hydrogen sensor provided in an embodiment of the present application.

[0018] Figure Number: 100. Magnesium-based thin film hydrogen sensor; 1. Insulating layer; 2. First hydrogen-sensitive resistor; 3. Second hydrogen-sensitive resistor; 4. First reference resistor; 5. Second reference resistor; 6. Hydrogen-sensitive layer; 61. Chromium thin film layer; 62. Magnesium-based thin film layer; 63. Palladium thin film layer; 7. Barrier layer; 8. First electrode; 9. Second electrode; 10. Third electrode; 11. Fourth electrode; 12. Substrate. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the drawings and embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments of the present application, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present application. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0020] It should be noted that if there are descriptions involving "first", "second", etc. in the implementation of this application, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance and implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the fact that ordinary technicians in the field can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0021] See also Figure 1The embodiment of the present application provides a magnesium-based thin film hydrogen sensor 100, including an insulating layer 1 and a first hydrogen-sensitive resistor 2, a second hydrogen-sensitive resistor 3, a first reference resistor 4, and a second reference resistor 5 arranged on the insulating layer 1, wherein the first hydrogen-sensitive resistor 2, the second hydrogen-sensitive resistor 3, the first reference resistor 4, and the second reference resistor 5 form a Wheatstone bridge structure. Among them, one end of the first hydrogen-sensitive resistor 2 is connected to the first reference resistor 4 through a first electrode 8, and the other end is connected to the second reference resistor 5 through a second electrode 9, one end of the second hydrogen-sensitive resistor 3 is connected to the second reference resistor 5 through a third electrode 10, and the other end is connected to the first reference resistor 4 through a fourth electrode 11.

[0022] For further information, see Figure 2 The first hydrogen-sensitive resistor 2 and the second hydrogen-sensitive resistor 3 both include a hydrogen-sensitive layer 6, and the first reference resistor 4 and the second reference resistor 5 both include a hydrogen-sensitive layer 6 and a barrier layer 7 disposed on the hydrogen-sensitive layer 6. The electrical properties of the hydrogen-sensitive layer 6 are related to the hydrogen concentration on the surface of the hydrogen-sensitive layer 6, and the barrier layer 7 can prevent the hydrogen-sensitive layer 6 in the first reference resistor 4 and the second reference resistor 5 from contacting with hydrogen, and will not be affected by changes in the external hydrogen concentration.

[0023] When the magnesium-based thin film hydrogen sensor in the embodiment of the present application is placed in an environment containing a certain concentration of hydrogen, when the hydrogen sensitive layer 6 of the first hydrogen sensitive resistor 2 and the hydrogen sensitive layer 6 of the second hydrogen sensitive resistor 3 come into contact with hydrogen, the hydrogen molecules will be adsorbed on the surface of the air sensitive layer, and then dissociate into hydrogen atoms, penetrate into the interior of the film, causing the atomic lattice of the film to be distorted, and even forming metal hydrides, so that the electrical properties of the film (the first hydrogen sensitive resistor 2 and the second hydrogen sensitive resistor 3) are changed, and the first reference resistor 4 and the second reference resistor 5 are isolated from the contact of hydrogen with the hydrogen sensitive layer in the first reference resistor 4 and the second reference resistor 5 under the action of the barrier layer, and the electrical properties of the first reference resistor 4 and the second reference resistor 5 will not change, and then the hydrogen concentration in the environment containing hydrogen can be judged by detecting the change in the electrical properties of the first hydrogen sensitive resistor 2 and the second hydrogen sensitive resistor 3 (mainly referring to the change in resistivity).

[0024] Specifically, see Figure 4 , Figure 4 R1 represents the first hydrogen sensitive resistor 2, R2 represents the first reference resistor 4, R3 represents the second reference resistor 5, and R4 represents the second hydrogen sensitive resistor 3. R1, R2, R3 and R4 are electrically connected to form a Wheatstone bridge structure. in Indicates the access voltage when connecting R1, R2, R3 and R4 to the power supply, U out It represents the output voltage of the half bridge of the Wheatstone bridge composed of R1, R2, R3 and R4, U R1, U R2 , U R3 , U R4 They represent the voltages of R1, R2, R3 and R4 respectively, ΔR represents the resistance change of the hydrogen sensitive resistor under a certain hydrogen concentration, ΔU out Indicates the output voltage change, U 0 represents the initial output voltage. ; ; ; ; ; because , , , ,get: ; ; ; The sensitivity is then obtained as: .

[0025] By forming a Wheatstone bridge structure with the first hydrogen sensitive resistor 2, the second hydrogen sensitive resistor 3, the first reference resistor 4 and the second reference resistor 5, the zero drift of the magnesium-based thin film hydrogen sensor during the hydrogen sensitivity test due to environmental influences (for example, changes in ambient temperature and humidity) can be alleviated to a certain extent; at the same time, the voltage measurement method is more accurate than the resistance measurement method, so that the magnesium-based thin film hydrogen sensor can measure the hydrogen concentration with higher accuracy.

[0026] In some embodiments, Figure 5As shown, the structure of the hydrogen sensitive layer 6 is a comb-like structure, the size of the comb-like structure is 90×85-90×350 mm, and the comb-like structure includes 20-80 comb teeth. For example, the number of comb teeth can be any integer such as 20, 30, 35, 40, 46, 50, 57, 60, 68, 70, 73 or 80. The comb teeth are evenly distributed, and the gap between two adjacent comb teeth is 50-200 μm, for example, the gap between two adjacent comb teeth is 50 μm, 80 μm, 100 μm, 120 μm, 150 μm, 160 μm, 180 μm or 200 μm, etc. Further, the comb teeth include two side teeth and a middle tooth between the two side teeth, and the width of the side teeth (edge ​​tooth width) is 300-550 μm, for example, the width of the side teeth can be 300 μm, 350 μm, 400 μm, 450 μm, 500 μm or 550 μm, etc. The width of the middle teeth is 50-200 μm, for example, the width of the middle teeth (tooth width) is 50 μm, 100 μm, 150 μm or 200 μm, etc. Providing the hydrogen sensitive layer 6 with a comb-like structure can increase the contact area between the hydrogen sensitive layer 6 and hydrogen, thereby enhancing the sensitivity of the magnesium-based thin film hydrogen sensor 100 to hydrogen concentration.

[0027] In some embodiments, the structure of the hydrogen sensitive layer 6 is as follows: Figure 3 The serpentine wire structure shown has an overall size of 10×10 mm, a width of 10-100 μm, and a gap between adjacent parts of the serpentine wire structure of 20-100 μm. This arrangement can accommodate more hydrogen sensitive layers 6 in the same area to increase the contact area between the hydrogen sensitive layer 6 and hydrogen, thereby enhancing the sensitivity of the magnesium-based thin film hydrogen sensor 100 to hydrogen concentration.

[0028] In some embodiments, please refer to Figure 4 The hydrogen sensitive layer 6 includes a chromium film layer 61, a magnesium-based film layer 62, and a palladium film layer 63 which are stacked in sequence. Since the magnesium-based film layer 62 is not firmly bonded to the surface of the insulating layer 1, and the chromium film layer 61 has good adhesion, by providing the chromium film layer 61 as an intermediate layer, the bonding force between the magnesium-based film layer 62 and the insulating layer 1 can be improved, thereby improving the stability of the magnesium-based film hydrogen sensor 100.

[0029] In some embodiments, the thickness of the chromium film layer 61 is 5-10 nm, for example, the thickness of the chromium film layer 61 is 5 nm, 6 nm, 7 nm, 8 nm, 9 nm or 10 nm, etc. The chromium film layer 61 of this thickness can provide sufficient adhesion for the magnesium-based film layer 62 while maintaining good conductivity.

[0030] Furthermore, the magnesium-based film layer 62 and the palladium film layer 63 can react with hydrogen. When the magnesium-based film hydrogen sensor 100 is in an environment containing a certain concentration of hydrogen, hydrogen molecules can be adsorbed on the surface of the palladium film layer 63, and dissociate into hydrogen atoms and diffuse into the atomic lattices of the magnesium-based film layer 62 and the palladium film layer 63, causing the volume of the lattice to change and a phase change to occur, so that the electrical properties of the magnesium-based film layer 62 and the palladium film layer 63 change (mainly the change in conductivity leads to a change in resistance), that is, the electrical properties of the first hydrogen-sensitive resistor 2 and the second hydrogen-sensitive resistor 3 change. By detecting the change in the electrical properties of the first hydrogen-sensitive resistor 2 and the second hydrogen-sensitive resistor 3, the hydrogen concentration in the external environment is finally determined.

[0031] In some embodiments, the thickness of the palladium film layer 63 is 5-10 nm, for example, the thickness of the palladium film layer 63 is 5 nm, 6 nm, 7 nm, 8 nm, 9 nm or 10 nm. The thickness of the magnesium-based film layer 62 is 30-150 nm, for example, the thickness of the magnesium-based film layer 62 is 30 nm, 50 nm, 100 nm, 150 nm, etc.

[0032] In some embodiments, the magnesium-based film layer 62 includes magnesium and at least one of palladium, iron, and rhenium. Preferably, the magnesium-based film layer 62 is a pure magnesium film, a magnesium-palladium alloy, a magnesium-iron alloy, or a magnesium-rhenium alloy. In order to ensure the sensitivity of the magnesium-based film layer 62 to hydrogen, the mass content of magnesium in the magnesium-based film layer 62 is preferably greater than or equal to 50%. For example, the mass content of magnesium in the magnesium-based film layer 62 is 50%, 60%, 70%, 80%, or 90%, etc.

[0033] In some embodiments, the thickness of the barrier layer 7 is 200-300 nm, for example, the thickness of the barrier layer 7 is 200 nm, 250 nm or 300 nm. The barrier layer 7 is silicon carbide or silicon dioxide. Both silicon carbide and silicon dioxide can make the barrier layer block the hydrogen sensitive layer 6 of the first reference resistor 4 and the hydrogen sensitive layer 6 of the second reference resistor 5 from contacting with hydrogen in the environment.

[0034] In some embodiments, the first electrode, the second electrode, the third electrode and the fourth electrode include a chromium intermediate layer and a gold electrode layer, wherein the thickness of the chromium intermediate layer is 3-10 nm, for example, the thickness of the chromium intermediate layer is 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm or 10 nm. The thickness of the gold electrode layer is 150-300 nm, for example, the thickness of the gold electrode layer is 150 nm, 200 nm, 250 nm or 300 nm, etc.

[0035] In some embodiments, the thickness of the insulating layer 1 is 300-500 nm, for example, the thickness of the insulating layer 1 is 300 nm, 350 nm, 400 nm, 450 nm or 500 nm. The insulating layer 1 is made of silicon dioxide by a thermal oxidation process.

[0036] In some embodiments, Figure 2 As shown, the magnesium-based thin film hydrogen sensor 100 further includes a substrate layer 12, the insulating layer 1 is arranged on the substrate layer 12, and the substrate layer 12 is made of single-element silicon, which is a silicon substrate layer.

[0037] The present application also provides a method for preparing the magnesium-based thin film hydrogen sensor as described above in the present application, comprising the steps of: The hydrogen sensitive layer is patterned on the insulating layer by a photolithography process, and the hydrogen sensitive layer is prepared by a magnetron sputtering method; The first electrode, the second electrode, the third electrode, and the fourth electrode are patterned by a photolithography process, and the first electrode, the second electrode, the third electrode, and the fourth electrode are prepared by a magnetron sputtering method or an evaporation method; The barrier layer is patterned on the hydrogen sensitive layer of the first reference resistor and the hydrogen sensitive layer of the second reference resistor by a photolithography process, and the barrier layer is prepared by a magnetron sputtering method or a chemical vapor deposition method.

[0038] In some embodiments, the specific steps of patterning the hydrogen sensitive layer on the insulating layer may be: spin coating photoresist on the insulating layer, designing a mask according to precision requirements, and patterning the hydrogen sensitive layer by ultraviolet exposure and development. The first electrode, the second electrode, the third electrode, the fourth electrode, and the barrier layer may be patterned in a similar manner.

[0039] The embodiment of the present application also provides an application of the magnesium-based thin film hydrogen sensor described above in the embodiment of the present application in detecting hydrogen concentration.

[0040] For example, a magnesium-based thin film hydrogen sensor can be placed in a gas-sensitive test chamber, and hydrogen with gradient concentrations (such as 100ppm, 200ppm, 300ppm, 400ppm, 500ppm, 600ppm, 700ppm, 800ppm, 900ppm or 1000ppm) can be introduced into the chamber to measure the voltage of the magnesium-based thin film hydrogen sensor at different concentrations for calibration. When measuring hydrogen of unknown concentration, the hydrogen concentration can be determined based on the corresponding voltage change.

[0041] The following is further described by means of specific examples.

[0042] Example 1

[0043] (1) A 300nm thick silicon dioxide layer was prepared on a silicon substrate by thermal oxidation, followed by annealing to obtain a high-quality silicon dioxide insulating layer. The substrate was cleaned in an ultrasonic cleaner using acetone, anhydrous ethanol, and deionized water, and then dried using a nitrogen gun. The water was evaporated on a heating table to obtain a clean substrate.

[0044] (2) Use RDP-8003 photoresist to coat at 4000r / min for 1min, pre-bake at 100℃ for 30s, install the mask on the photolithography machine, UV-expose for 10s, post-bake at 100℃ for 60s, develop with ZX-238 developer for 60s, wash with deionized water for 2min, and harden at 100℃ for 60s. Then use a DC magnetron sputtering instrument to deposit a 5nm chromium film layer, a 30nm magnesium-palladium film layer, and a 5nm palladium film layer in sequence, where the magnesium content in the magnesium-based film layer is 90%. After deposition, use acetone solution for stripping to obtain a hydrogen sensitive layer.

[0045] (3) Similarly, RDP-8003 photoresist was used to coat at 4000 r / min for 1 min, pre-baked at 100°C for 30 s, mounted on the photolithography machine, exposed to UV light for 15 s, post-baked at 100°C for 60 s, developed with ZX-238 developer for 60 s, cleaned with deionized water for 2 min, and hardened at 100°C for 60 s. Then, 5 nm of elemental chromium and 200 nm of elemental gold were deposited in sequence using a DC magnetron sputtering apparatus, and after deposition, an acetone solution was used for stripping to obtain a first electrode, a second electrode, a third electrode, and a fourth electrode.

[0046] (4) Similarly, RDP-8003 photoresist was used to coat at 4000 r / min for 1 min, followed by pre-baking at 100°C for 30 s, the mask was mounted on the photolithography machine, UV-exposed for 10 s, post-baked at 100°C for 60 s, developed with ZX-238 developer for 60 s, cleaned with deionized water for 2 min, and hardened at 100°C for 60 s. Then, 300 nm of silicon nitride was deposited using a magnetron sputtering apparatus, and after deposition, an acetone solution was used for stripping to obtain a barrier layer.

[0047] (5) The product of (4) was placed in a tube furnace and annealed at 300° C. for 5 h in an inert gas atmosphere, and then cooled in the furnace to obtain a magnesium-based thin film hydrogen sensor.

[0048] Example 2

[0049] (1) A 400nm thick silicon dioxide layer was prepared on a silicon substrate by thermal oxidation, followed by annealing to obtain a high-quality silicon dioxide insulating layer. The substrate was cleaned in an ultrasonic cleaner using acetone, anhydrous ethanol, and deionized water, then dried using a nitrogen gun and heated on a heating table to evaporate the water to obtain a clean substrate.

[0050] (2) Use RDP-8003 photoresist to coat at 5000r / min for 1min, pre-bake at 100℃ for 30s, install the mask on the photolithography machine, UV-expose for 10s, post-bake at 100℃ for 60s, develop with ZX-238 developer for 60s, rinse with deionized water for 2min, and harden at 100℃ for 60s. Then use a DC magnetron sputtering instrument to deposit a 5nm chromium film layer, a 90nm magnesium-palladium film layer, and a 7nm palladium film layer in sequence, where the magnesium content in the magnesium-based film layer is 90%. After deposition, use acetone solution for stripping to obtain a hydrogen sensitive layer.

[0051] (3) Similarly, RDP-8003 photoresist was used to coat at 5000 r / min for 1 min, pre-baked at 100°C for 30 s, mounted on the photolithography machine, exposed to UV light for 15 s, post-baked at 100°C for 60 s, developed with ZX-238 developer for 60 s, cleaned with deionized water for 2 min, and hardened at 100°C for 60 s. Then, 5 nm of elemental chromium and 240 nm of elemental gold were deposited in sequence using a DC magnetron sputtering apparatus, and after deposition, an acetone solution was used for stripping to obtain a first electrode, a second electrode, a third electrode, and a fourth electrode.

[0052] (4) Similarly, RDP-8003 photoresist was used to coat the surface at 5000 r / min for 1 min, followed by pre-baking at 100°C for 30 s, the mask was mounted on the photolithography machine, UV-exposed for 10 s, post-baked at 100°C for 60 s, developed with ZX-238 developer for 60 s, cleaned with deionized water for 2 min, and hardened at 100°C for 60 s. Then, 300 nm of silicon nitride was deposited using a magnetron sputtering apparatus, and after deposition, an acetone solution was used for stripping to obtain a barrier layer.

[0053] (5) The product of (4) was placed in a tube furnace and annealed at 370° C. for 5 h in an inert gas atmosphere, and then cooled in the furnace to obtain a magnesium-based thin film hydrogen sensor.

[0054] Example 3

[0055] (1) A 450nm thick silicon dioxide layer was prepared on a silicon substrate by thermal oxidation, followed by annealing to obtain a high-quality silicon dioxide insulating layer. The substrate was cleaned in an ultrasonic cleaner using acetone, anhydrous ethanol, and deionized water, and then dried using a nitrogen gun. The water was evaporated on a heating table to obtain a clean substrate.

[0056] (2) Use RDP-8003 photoresist to coat at 4500r / min for 1min, pre-bake at 100℃ for 30s, install the mask on the photolithography machine, UV-expose for 10s, post-bake at 100℃ for 60s, develop with ZX-238 developer for 60s, wash with deionized water for 2min, and harden at 100℃ for 60s. Then use a DC magnetron sputtering instrument to deposit a 5nm chromium film layer, a 110nm magnesium-palladium film layer, and an 8nm palladium film layer in sequence, where the magnesium content in the magnesium-based film layer is 90%. After deposition, use acetone solution for stripping to obtain a hydrogen sensitive layer.

[0057] (3) Similarly, RDP-8003 photoresist was used to coat at 4500r / min for 1min, pre-baked at 100℃ for 30s, mounted on the photolithography machine, exposed to UV light for 15s, post-baked at 100℃ for 60s, developed with ZX-238 developer for 60s, cleaned with deionized water for 2min, and hardened at 100℃ for 60s. Then, 5nm of elemental chromium and 260nm of elemental gold were deposited in sequence using a DC magnetron sputtering apparatus, and after deposition, an acetone solution was used for stripping to obtain the first electrode, the second electrode, the third electrode, and the fourth electrode.

[0058] (4) Similarly, use RDP-8003 photoresist to coat at 5000r / min for 1min, then pre-bake at 100℃ for 30s, install the mask on the photolithography machine, UV exposure for 10s, post-bake at 100℃ for 60s, develop with ZX-238 developer for 60s, wash with deionized water for 2min, and harden at 100℃ for 60s. Then use magnetron sputtering to deposit 300nm of silicon dioxide, and after deposition, use acetone solution for stripping to obtain a barrier layer.

[0059] (5) The product of (4) was placed in a tube furnace and annealed at 400° C. for 5 h in an inert gas atmosphere, and then cooled in the furnace to obtain a magnesium-based thin film hydrogen sensor.

[0060] Example 4

[0061] (1) A 500nm thick silicon dioxide layer was prepared on a silicon substrate by thermal oxidation, followed by annealing to obtain a high-quality silicon dioxide insulating layer. The substrate was cleaned in an ultrasonic cleaner using acetone, anhydrous ethanol, and deionized water, and then dried using a nitrogen gun. The water was evaporated on a heating table to obtain a clean substrate.

[0062] (2) Use RDP-8003 photoresist to coat at 6000r / min for 1min, pre-bake at 100℃ for 30s, install the mask on the photolithography machine, UV-expose for 10s, post-bake at 100℃ for 60s, develop with ZX-238 developer for 60s, wash with deionized water for 2min, and harden at 100℃ for 60s. Then use a DC magnetron sputtering instrument to deposit a 5nm chromium film layer, a 150nm magnesium-palladium film layer, and a 10nm palladium film layer in sequence, where the magnesium content in the magnesium-based film layer is 90%. After deposition, use acetone solution for stripping to obtain a hydrogen sensitive layer.

[0063] (3) Similarly, RDP-8003 photoresist was used to coat at 6000 r / min for 1 min, pre-baked at 100°C for 30 s, mounted on the photolithography machine, exposed to UV light for 15 s, post-baked at 100°C for 60 s, developed with ZX-238 developer for 60 s, cleaned with deionized water for 2 min, and hardened at 100°C for 60 s. Then, 5 nm of elemental chromium and 300 nm of elemental gold were sequentially deposited using a DC magnetron sputtering apparatus, and after deposition, an acetone solution was used for stripping to obtain a first electrode, a second electrode, a third electrode, and a fourth electrode.

[0064] (4) Similarly, RDP-8003 photoresist was used to coat the surface at 6000 r / min for 1 min, followed by pre-baking at 100°C for 30 s, the mask was mounted on the photolithography machine, UV-exposed for 10 s, post-baked at 100°C for 60 s, developed with ZX-238 developer for 60 s, cleaned with deionized water for 2 min, and hardened at 100°C for 60 s. Then, 300 nm of silicon dioxide was deposited using a magnetron sputtering apparatus, and after deposition, an acetone solution was used for stripping to obtain a barrier layer.

[0065] (5) The product of (4) was placed in a tube furnace and annealed at 450° C. for 5 h in an inert gas atmosphere, and then cooled in the furnace to obtain a magnesium-based thin film hydrogen sensor.

[0066] Test Example 1 The existing resistive palladium thin film hydrogen sensor was tested using the Keysight B1500A semiconductor parameter analyzer (combined with a four-probe measurement station). The response to different concentrations of hydrogen in an argon atmosphere at 60°C is shown in the following figure. Figure 6 As shown. Figure 6 It can be seen that under different hydrogen concentrations, the zero drift of the existing resistive palladium thin film hydrogen sensor is quite serious.

[0067] Test Example 2 The response of the magnesium-based thin film hydrogen sensor prepared in Example 1 to different concentrations of hydrogen in an argon atmosphere at 30°C was tested using a Keysight B1500A semiconductor parameter analyzer (combined with a four-probe measurement station). The results are as follows: Figure 7 As shown. Figure 7 It can be seen that at a lower temperature (30°C), the magnesium-based thin film hydrogen sensor prepared in Example 1 exhibits a rapid response to hydrogen, with a response time of 60-135s, and the zero drift is significantly reduced compared with the existing resistive palladium thin film magnesium-based thin film hydrogen sensor in Test Example 1.

[0068] In summary, the magnesium-based thin film hydrogen sensor of the present application includes a Wheatstone bridge structure composed of a first hydrogen-sensitive resistor, a second hydrogen-sensitive resistor, a first reference resistor and a second reference resistor. When the magnesium-based thin film hydrogen sensor is exposed to hydrogen, the electrical properties of the first hydrogen-sensitive resistor and the second hydrogen-sensitive resistor change after contacting with hydrogen. The first reference resistor and the second reference resistor cannot contact with hydrogen due to the effect of the barrier layer. Based on this, the concentration of hydrogen can be determined by detecting the change in the output voltage of the magnesium-based thin film hydrogen sensor. In the magnesium-based thin film hydrogen sensor of the present application, only hydrogen can affect the electrical properties of the first hydrogen-sensitive resistor and the second hydrogen-sensitive resistor, and by constructing a Wheatstone bridge structure in the magnesium-based thin film hydrogen sensor, the subtle changes in the electrical properties of the first hydrogen-sensitive resistor and the second hydrogen-sensitive resistor can be measured, thereby improving the sensitivity and accuracy of the magnesium-based thin film hydrogen sensor in detecting hydrogen concentration. At the same time, the magnesium-based thin film hydrogen sensor of the present application has low operating power, low operating temperature and simple preparation process.

[0069] It should be understood that the application of the present application is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to this application.

Claims

1. A magnesium-based thin film hydrogen sensor, characterized in that: It includes an insulating layer and a first hydrogen-sensitive resistor, a second hydrogen-sensitive resistor, a first reference resistor and a second reference resistor arranged on the insulating layer, wherein the first hydrogen-sensitive resistor, the second hydrogen-sensitive resistor, the first reference resistor and the second reference resistor form a Wheatstone bridge structure; One end of the first hydrogen-sensitive resistor is connected to the first reference resistor through a first electrode, and the other end is connected to the second reference resistor through a second electrode; one end of the second hydrogen-sensitive resistor is connected to the second reference resistor through a third electrode, and the other end is connected to the first reference resistor through a fourth electrode; The first hydrogen-sensitive resistor and the second hydrogen-sensitive resistor both include a hydrogen-sensitive layer; the first reference resistor and the second reference resistor both include a hydrogen-sensitive layer and a barrier layer covering the hydrogen-sensitive layer; The change in the electrical properties of the hydrogen sensitive layer is related to the concentration of hydrogen on the surface of the hydrogen sensitive layer, and the barrier layer blocks the hydrogen sensitive layer from contacting with hydrogen.

2. The magnesium-based thin film hydrogen sensor according to claim 1, characterized in that: The hydrogen sensitive layer has a comb-like structure, the comb-like structure includes 20-80 comb teeth, the comb teeth are evenly distributed, and the gap between two adjacent comb teeth is 50-200 μm; The comb teeth include two side teeth and a middle tooth located between the two side teeth. The width of the side teeth is 300-550 μm, and the width of the middle teeth is 50-200 μm.

3. The magnesium-based thin film hydrogen sensor according to claim 1, characterized in that: The hydrogen sensitive layer comprises a magnesium-based thin film layer, and the thickness of the magnesium-based thin film layer is 30-150 nm; The magnesium-based film layer includes a pure magnesium film or a magnesium alloy, the magnesium alloy is selected from a magnesium-palladium alloy, a magnesium-iron alloy or a magnesium-rhenium alloy, and the mass content of magnesium in the magnesium alloy is greater than or equal to 50%.

4. The magnesium-based thin film hydrogen sensor according to claim 3, characterized in that: The hydrogen sensitive layer further comprises a chromium thin film layer and a palladium thin film layer, wherein the chromium thin film layer is disposed on the insulating layer, the magnesium-based thin film layer is disposed on the chromium thin film layer, and the palladium thin film layer is disposed on the magnesium-based thin film layer; The thickness of the chromium thin film layer is 3-10 nm, and the thickness of the palladium thin film layer is 5-10 nm.

5. The magnesium-based thin film hydrogen sensor according to claim 1, characterized in that: The barrier layer has a thickness of 200-300 nm and comprises silicon carbide or silicon dioxide.

6. The magnesium-based thin film hydrogen sensor according to claim 1, characterized in that: The first electrode, the second electrode, the third electrode and the fourth electrode all include a chromium intermediate layer and a gold electrode layer disposed on the chromium intermediate layer. The thickness of the chromium intermediate layer is 3-10 nm, and the thickness of the gold electrode layer is 150-300 nm.

7. The magnesium-based thin film hydrogen sensor according to claim 1, characterized in that: The thickness of the insulating layer is 300-500 nm, and the insulating layer is made of silicon dioxide by a thermal oxidation process.

8. The magnesium-based thin film hydrogen sensor according to claim 1, characterized in that: The magnesium-based thin film hydrogen sensor comprises a substrate layer, the insulating layer is arranged on the substrate layer, and the substrate layer is a silicon substrate layer.

9. A method for preparing a magnesium-based thin film hydrogen sensor according to claim 1, characterized in that: Includes steps: A hydrogen sensitive layer is prepared on the insulating layer by magnetron sputtering to obtain a first hydrogen sensitive resistor, a second hydrogen sensitive resistor, a first reference resistor precursor and a second reference resistor precursor; Forming a first electrode, a second electrode, a third electrode, and a fourth electrode on the insulating layer by magnetron sputtering or evaporation; A barrier layer is formed on the hydrogen sensitive layer of the first reference resistor precursor and the hydrogen sensitive layer of the second reference resistor precursor by magnetron sputtering or chemical vapor deposition.

10. Use of the magnesium-based thin film hydrogen sensor according to any one of claims 1 to 8 in detecting hydrogen concentration.

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