A semiconductor bridge current protection method based on vanadium dioxide thick film thermistor

Abstract

The present invention belongs to the field of semiconductor bridge current protection, and specifically relates to a semiconductor bridge current protection method based on vanadium dioxide thick film thermistor. First, copper, nickel, and gold interdigital electrodes are deposited and grown on an alumina ceramic substrate, and then a methanol solution of acetylacetonato vanadium is sprayed on the surface of the heated interdigital electrodes to obtain a vanadium dioxide thermistor device, which is connected in parallel with the semiconductor bridge to achieve semiconductor bridge thermistor current protection. The present invention can synthesize vanadium dioxide with a relatively single valence state by adjusting the synthesis method and process, and realize the one-step synthesis of M-phase vanadium dioxide on the interdigital electrodes. The vanadium dioxide prepared by this method avoids the cumbersome process of first preparing vanadium dioxide powder and then transplanting it on the surface of the interdigital electrodes, and can also make the vanadium dioxide more firmly bonded to the surface of the interdigital electrodes.

Description

Technical Field

[0001] The invention belongs to the field of semiconductor bridge current protection, and in particular relates to a semiconductor bridge current protection method based on a vanadium dioxide thick film thermistor. Background Art

[0002] The semiconductor bridge (SCB) is an important component of the transducer component. In an increasingly complex electromagnetic environment, the transducer will form an equivalent antenna with the circuit, absorb the energy in the electromagnetic field and convert it into heat energy, affecting the safety of the device. Many equipments have put forward a safety current requirement of 1A / 5min for transducer components. When a current of 1A is passed through, the temperature of the semiconductor bridge is required not to rise to the upper limit required by the device within 5 minutes. In order to effectively protect the semiconductor bridge from electromagnetic interference, a negative temperature coefficient thermistor (NTC) is usually selected to form a parallel circuit with the semiconductor bridge. As the current continues to be input, the temperature of the semiconductor bridge rises, while the NTC resistance gradually decreases, and the current flowing through the semiconductor bridge decreases, thereby achieving the purpose of lowering the temperature. However, as the device size requirements become smaller and smaller, the NTC resistor is incompatible with the transducer component manufacturing process and cannot be produced in an integrated manner. The metal-insulator transition (MIT) material vanadium dioxide (VO2) has a suitable phase transition temperature of 68°C. Its conductivity can undergo reversible and huge changes with temperature changes. Its preparation process is compatible with the semiconductor bridge integrated preparation process. It can be connected in parallel with the semiconductor bridge as a very perfect thermistor to prepare energy conversion components. However, vanadium dioxide can be prepared by sol-gel method, vapor deposition method and hydrothermal method. Depending on the vanadium source and the reducing agent, the valence state of the synthetic product will be different, forming other oxides or oxide mixtures of vanadium. Summary of the invention

[0003] In view of the above-mentioned defects of the prior art, the present invention realizes current protection for the semiconductor bridge by preparing an M-phase vanadium dioxide thin film, and forms a parallel circuit between the vanadium dioxide thermistor and the semiconductor bridge, and utilizes the characteristics of the M-phase vanadium dioxide being insulated at low temperatures and transforming into a metal phase at high temperatures, so as to play a shunting role on the semiconductor bridge at high temperatures and reduce damage to the semiconductor bridge. The present invention can synthesize vanadium dioxide with a relatively single valence state by adjusting the synthesis method and process, and realizes the synthesis of M-phase vanadium dioxide on the interdigital electrode in one step. The vanadium dioxide prepared by this method avoids the cumbersome process of first preparing vanadium dioxide powder and then transplanting it on the surface of the interdigital electrode, and can also make the vanadium dioxide more firmly bonded to the surface of the interdigital electrode to form a thermistor device.

[0004] The present invention provides a semiconductor bridge current protection method based on a vanadium dioxide thick film thermistor, comprising the following steps: S1, dissolving vanadium acetylacetonate in a methanol solution to obtain a methanol solution of vanadium acetylacetonate;

[0005] S2, obtaining interdigital electrodes, and heating the interdigital electrodes to keep the temperature of the interdigital electrodes at 300-400 degrees Celsius;

[0006] S3, spraying the methanol solution of vanadyl acetylacetonate obtained in step S1 on the surface of the interdigital electrode in step S2,

[0007] During the spraying process, the temperature of the interdigital electrode is maintained at 300-400 degrees Celsius, and an M-phase vanadium oxide film with a thickness of 2-5 um is deposited on the surface of the interdigital electrode by spraying;

[0008] S4, after the spraying is completed, the interdigital electrodes and the vanadium oxide film are annealed together, and naturally cooled to room temperature to obtain a thermistor device; the thermistor device includes the interdigital electrodes and the vanadium oxide film deposited on the interdigital electrodes;

[0009] S5. Connecting the thermistor device in parallel with the semiconductor bridge to implement semiconductor bridge thermistor current protection.

[0010] Preferably, step S2 specifically includes the following steps: placing the substrate with the interdigital electrodes plated on the surface on an electric heating plate for heating, and controlling the surface temperature of the electric heating plate to be between 300 and 400 degrees Celsius.

[0011] Preferably, the substrate is any one of an alumina ceramic and a silicon substrate with an oxide layer grown on the surface.

[0012] Preferably, the spraying in step S3 is specifically performed by spraying through an atomizing nozzle.

[0013] Preferably, the spraying by an atomizing nozzle specifically comprises the following steps: controlling the distance between the atomizing nozzle and the upper surface of the interdigital electrode to be 10-20 cm; controlling the spraying spray volume to be 20-50 ml / min, and controlling the spraying time to be 30-40 minutes.

[0014] Preferably, the interdigital electrodes are any one of copper interdigital electrodes, nickel interdigital electrodes and gold interdigital electrodes.

[0015] The present invention has the following effects relative to the prior art:

[0016] The prepared vanadium dioxide has a dense structure, strong bonding with the substrate, and basically presents an M phase. The material prepared in this way has good conductivity and good stability at high temperatures.

[0017] The vanadium dioxide is prepared on the surface of the interdigital electrode in one step, which shortens the preparation process of the thermistor device and also improves the stability of the thermistor device.

[0018] The spraying process provided by the present invention for depositing vanadium dioxide has strong scalability. For example, by adding elements such as chromium and cadmium during the spraying process, the phase change temperature can be further adjusted to improve the temperature application range of the device.

[0019] The thickness of the film layer can be adjusted by spraying. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific implementation of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the specific implementation or the prior art description. Some specific embodiments of the present invention will be described in detail in an exemplary but not restrictive manner with reference to the drawings. The same reference numerals in the drawings indicate the same or similar components or parts. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0021] Figure 1 This is a morphology diagram of vanadium dioxide; it can be seen from the figure that a large number of vanadium dioxide particles are deposited on the finger electrodes of the interdigitated electrode and in the gaps between the electrodes, and the contact between the particles is good.

[0022] Figure 2 This is a side view of vanadium dioxide; it can be seen that under the deposition conditions, the film thickness is about 3um, the structure is dense, and the contact with the substrate is close.

[0023] Figure 3 This is the XRD diagram of M-phase vanadium dioxide; the peak of the sample in the figure is sharp, indicating that the sample has good crystallinity. Except for the peak of the substrate Al2O3, the other peaks in the sample are consistent with the peak positions of the M-phase vanadium dioxide standard card, indicating that the prepared vanadium dioxide film is M-phase.

[0024] Figure 4 The resistance curve of the vanadium dioxide thermistor device changes with temperature. When the device is at low temperature, the vanadium dioxide is in an insulating state with a resistance of 240Ω. After heating, the resistance decreases until the phase change ends, and the vanadium dioxide changes to a metal phase with a resistance of 5Ω. When one device is connected in parallel with an SCB (1Ω), it can shunt 1 / 6. When two thermistors are connected in parallel, it can shunt 2 / 7, which can significantly reduce the heat on the SCB.

[0025] Figure 5 This is a graph showing the relationship between temperature and power-on time at a fixed current before the semiconductor bridge is connected in parallel with the vanadium dioxide thermistor. The curves of different colors in the figure represent the currents of 0.8A, 1.0A and 1.2A. It can be seen from the figure that at a current of 0.8A, the temperature on the SCB gradually increases, gradually balances with the increase of power-on time, and stabilizes at 131°C; the equilibrium temperature is 186°C at a current of 1.0A; when the power-on time is 150s at a current of 1.2A, the SCB is broken due to the increase in temperature, damaged, and the temperature drops sharply.

[0026] Figure 6 This is a graph showing the relationship between temperature and power-on time at a fixed current after the semiconductor bridge and the vanadium dioxide thermistor are connected in parallel. The curves of different colors in the figure represent currents of 0.8A, 1.0A and 1.5A respectively. It can be seen from the figure that in the extremely short time when the current is applied, the temperature on the SCB rises rapidly, and as the vanadium dioxide undergoes a phase change, the current is divided by the vanadium dioxide thermistor, the temperature rise rate of the SCB slows down, and gradually stabilizes as the power-on time increases. The equilibrium temperature is 86°C at a current of 0.8A; the equilibrium temperature is 110°C at a current of 1.0A; and the equilibrium temperature is 180°C at a current of 1.5A. Comparison Figure 5 It can be seen from the equilibrium temperature in that the vanadium dioxide thermistor can effectively reduce the temperature on the SCB, play a protective role, and increase the safe current of the SCB. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application. Example

[0028] Step (1) Dissolve 2 g of vanadyl acetylacetonate in 50 ml of anhydrous methanol at room temperature;

[0029] Step (2) Place a ceramic sheet with interdigital electrodes on the surface on an electric heating plate, and control the surface temperature of the electric heating plate at 400 degrees Celsius. The interdigital electrodes used are 1 cm×1 cm alumina ceramic substrates, with 15 pairs of interdigital electrodes on the surface, with a line spacing of 50 um, a line width of 100 um, and a finger length of 7.7 mm;

[0030] Step (3) The methanol solution containing vanadyl acetylacetonate obtained in step 1 is sprayed onto the surface of the heated interdigital electrode through an atomizing nozzle, and the distance between the atomizing nozzle and the surface of the electric heating plate is 5 cm.

[0031] Step (4) The spraying volume is controlled to be 50 ml / min, the spraying time is about 40 minutes, and a vanadium oxide film with a thickness of about 3 um is prepared. The prepared film thickness is thicker than that of the PVD method, the process is simpler, and the preparation cost is lower.

[0032] Step (5) annealing the prepared film in an Ar2 atmosphere at 400 degrees Celsius for 3 hours. The vanadium dioxide film obtained after annealing is gray.

[0033] Step (6) After the spraying is completed, the electric heating plate stops heating and the device is naturally cooled to room temperature to obtain a thermistor device. The resistance of the prepared device is about 5Ω at room temperature.

[0034] Step (7) The thermistor device is connected in parallel with the semiconductor bridge. When the power is turned on for 5 minutes at a fixed current, it can be found that before the vanadium dioxide thermistor is connected in parallel, the temperature of the semiconductor bridge rises rapidly to above 200°C at a current of 1.2A. After the vanadium dioxide thermistor is connected in parallel, the temperature of the device can be effectively reduced. Under the test condition of 1.5A, the equilibrium temperature is still below 200°C. The prepared thermistor has a good current protection effect on SCB.

[0035] Comparative Example 1:

[0036] Step (1) Dissolve 2 g of vanadyl acetylacetonate in 50 ml of anhydrous methanol at room temperature;

[0037] Step (2) Place a ceramic sheet with interdigital electrodes on the surface on an electric heating plate, and control the surface temperature of the electric heating plate at 350 degrees Celsius. The interdigital electrodes used are 1 cm×1 cm alumina ceramic substrates, with 15 pairs of interdigital electrodes on the surface, with a line spacing of 50 um, a line width of 100 um, and a finger length of 7.7 mm;

[0038] Step (3) The methanol solution containing vanadyl acetylacetonate obtained in step 1 is sprayed onto the surface of the heated interdigital electrode through an atomizing nozzle, and the distance between the atomizing nozzle and the surface of the electric heating plate is 5 cm.

[0039] Step (4) The spraying volume is controlled to be 50 ml / min, the spraying time is about 20 minutes, and a vanadium oxide film with a thickness of about 1 um is prepared.

[0040] Step (5) annealing the prepared film in an Ar2 atmosphere at 400 degrees Celsius for 3 hours. The vanadium dioxide film obtained after annealing is gray.

[0041] Step (6) After the spraying is completed, the electric heating plate stops heating and the device is cooled naturally to room temperature to obtain a thermistor device. The resistance of the device prepared is about 9Ω at room temperature.

[0042] Step (7) In step 6, if the resistance does not drop below 5Ω, the shunt effect is not good and the SCB current safety test is not performed.

[0043] Comparative Example 2

[0044] The VO2 serpentine thermistor is prepared by magnetron sputtering, comprising the following steps:

[0045] Step (1): Use silicon as a substrate, clean it, and blow it dry with nitrogen for later use.

[0046] Step (2): Turn on the mechanical pump and evacuate to 20 Pa. Turn on the molecular pump and when the reading reaches 5.0×10 -4 Starting at 90 Pa, turn on the flow display and introduce argon gas.

[0047] Step (3): Set the substrate temperature to 60°C, pre-sputter the surface of the vanadium target for 20-30 minutes to remove contaminants or other oxides on the target surface. Pass oxygen with an oxygen to argon flow ratio of 0.01, set the substrate temperature to 300°C, use an AC target, and sputter for 30 minutes.

[0048] Step (4): The temperature is 400°C and annealed for 1 hour under a pure nitrogen atmosphere before cooling to room temperature and taking out the sample.

[0049] The film thickness of the prepared vanadium oxide thermistor device is 500nm, and the resistance after phase change is 15Ω. The shunting effect is not as good as that of a 3um thick film thermistor. Increasing the magnetron sputtering time can increase the film thickness, but this method not only increases the cost, but also increases the film stress and peels off from the substrate surface. Therefore, the magnetron sputtering method cannot prepare a film with too thick a thickness, and the effect of the prepared vanadium dioxide thermistor is currently not as good as the method described in this patent. The above is only a partial specific embodiment of the present invention, but the protection scope of the present invention is not limited to this. Any changes or substitutions that can be easily thought of by any person familiar with the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A semiconductor bridge current protection method based on vanadium dioxide thick film thermistor, characterized in that: The following steps are involved: S1, dissolving vanadium acetylacetonate in a methanol solution to obtain a methanol solution of vanadium acetylacetonate, wherein the molar concentration of vanadium acetylacetonate is 0.151M; S2, obtaining interdigital electrodes, and heating the interdigital electrodes to keep the temperature of the interdigital electrodes at 300 to 400 degrees Celsius; S3, spraying the methanol solution of vanadyl acetylacetonate obtained in step S1 on the surface of the interdigital electrode in step S2, During the spraying process, the temperature of the interdigital electrode is maintained at 300-400 degrees Celsius, and an M-phase vanadium oxide film with a thickness of 2-5 um is deposited on the surface of the interdigital electrode by spraying; S4, after the spraying is completed, the interdigital electrodes and the vanadium oxide film are annealed together, and naturally cooled to room temperature to obtain a thermistor device; the thermistor device includes the interdigital electrodes and the vanadium oxide film deposited on the interdigital electrodes; S5. Connecting the thermistor device in parallel with the semiconductor bridge to implement semiconductor bridge thermistor current protection.

2. A semiconductor bridge current protection method based on vanadium dioxide thick film thermistor according to claim 1, characterized in that: Step S2 specifically includes the following steps: placing the substrate with the interdigital electrodes plated on the surface on an electric heating plate for heating, and controlling the surface temperature of the electric heating plate to be between 300 and 400 degrees Celsius.

3. A semiconductor bridge current protection method based on vanadium dioxide thick film thermistor as claimed in claim 2, characterized in that: The substrate is any one of an aluminum oxide ceramic and a silicon substrate with an oxide layer grown on the surface.

4. A semiconductor bridge current protection method based on vanadium dioxide thick film thermistor according to claim 1, characterized in that: The spraying in step S3 is specifically performed by spraying through an atomizing nozzle.

5. A semiconductor bridge current protection method based on vanadium dioxide thick film thermistor as claimed in claim 4, characterized in that: The spraying by the atomizing nozzle specifically includes the following steps: controlling the distance between the atomizing nozzle and the upper surface of the interdigital electrode to be 5 to 20 cm; controlling the spraying amount to be 20 to 50 ml / min, and controlling the spraying time to be 30 to 40 minutes.

6. A semiconductor bridge current protection method based on vanadium dioxide thick film thermistor according to claim 1, characterized in that: The interdigital electrodes are any one of copper interdigital electrodes, nickel interdigital electrodes and gold interdigital electrodes.

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