High dielectric voltage-resistant composite insulating film and preparation method thereof, high dielectric voltage-resistant alloy thin film voltage-dependent resistor and preparation method thereof

Abstract

The application discloses a high dielectric voltage-resistant composite insulating film and a preparation method thereof, a high dielectric voltage-resistant alloy thin film pressure-sensitive core and a preparation method thereof. The composite insulating film comprises, from bottom to top, a tantalum pentoxide thin film, an aluminum oxide thin film and a silicon oxide thin film which are stacked in sequence, has the advantages of excellent dielectric voltage resistance, small thin film stress, good compactness and good adhesion, and the like. When the composite insulating film is used as an insulating layer between a functional material layer and a base material, the alloy thin film pressure-sensitive core constructed by the composite insulating film has the advantages of high dielectric voltage resistance, high detection precision, high sensitivity and good reliability in a harsh environment, and the like, and can meet the demand of special pressure monitoring for high-speed trains. Meanwhile, the alloy thin film pressure-sensitive core is prepared in the same vacuum cavity, and the thin film with small thin film stress, good compactness and good adhesion can be prepared, and then the alloy thin film pressure-sensitive core with more excellent performance can be obtained.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of pressure sensor manufacturing, and relates to a high dielectric voltage-resistant composite insulating film and a preparation method thereof, and a high dielectric voltage-resistant alloy thin film pressure-sensitive core and a preparation method thereof. BACKGROUND

[0002] With the rapid development of high-speed rail technology in China, high-speed rail networks are spread all over China, and the working environment thereof is increasingly diverse. In some specific occasions, pressure sensors with high dielectric voltage resistance are needed to monitor the healthy operation of locomotives. However, the existing pressure sensors have a maximum dielectric voltage resistance of only 500 V, which cannot meet the needs of the rapid development of high-speed rail technology. The fundamental reason is that the insulating layer arranged between the functional material layer and the substrate of the sensor still has defects such as insufficient dielectric voltage resistance performance and large film stress. At the same time, the insulating layer prepared by the existing preparation process still has defects such as poor compactness and poor adhesion, and the thermal expansion coefficients of the insulating layer, the substrate and the functional material layer are not matched, which leads to insufficient accuracy, temperature drift and stability of the sensor, and it is difficult to meet the requirements. Therefore, it is of great significance to develop an insulating layer with excellent dielectric voltage resistance performance, small film stress, good compactness and good adhesion for preparing a pressure sensor with high dielectric voltage resistance and promoting its wide application in the field of high-speed rail. SUMMARY

[0003] The technical problem to be solved by the present application is to overcome the shortcomings of the prior art, and to provide a high dielectric voltage-resistant composite insulating film with excellent dielectric voltage resistance performance, small film stress, good compactness and good adhesion, and a preparation method thereof. The present application also provides a high dielectric voltage-resistant alloy thin film pressure-sensitive core with high dielectric voltage resistance, high detection accuracy, high sensitivity and high reliability in harsh environments, and a preparation method thereof.

[0004] To solve the above technical problems, the technical scheme adopted by the present application is as follows:

[0005] A high dielectric voltage-resistant composite insulating film, which comprises, from bottom to top, a tantalum pentoxide thin film, an aluminum oxide thin film and a silicon oxide thin film stacked in sequence.

[0006] The high dielectric voltage-resistant composite insulating film is further improved, wherein the thickness of the tantalum pentoxide thin film is 50 nm to 150 nm; the thickness of the aluminum oxide thin film is 375 nm to 450 nm; and the thickness of the silicon oxide thin film is 2.5 pm to 3.5 pm.

[0007] As a general technical concept, the present application also provides a preparation method of the above-mentioned high dielectric voltage-resistant composite insulating film, which is prepared in the same vacuum chamber and comprises the following steps:

[0008] (1) using Ta2O5 target as sputtering source to carry out magnetron sputtering, depositing tantalum pentoxide film on the substrate material;

[0009] (2) using Al2O3 target as sputtering source to carry out magnetron sputtering, depositing aluminum oxide film on the tantalum pentoxide film;

[0010] (3) using SiO2 target as sputtering source to carry out magnetron sputtering, depositing silicon oxide film on the aluminum oxide film, obtaining high dielectric voltage-resistant composite insulating film.

[0011] The preparation method of the high dielectric voltage-resistant composite insulating film is further improved, in the (1), the process parameters of the magnetron sputtering are as follows: the sputtering base vacuum is lower than 1×10 -4 Pa, the sputtering parameter is 100W-150W, the Ar2 flow is 15sccm, oxygen is supplemented during the sputtering process, and the oxygen flow is 2sccm-4sccm; the purity of the Ta2O5 target is 99.99%.

[0012] The preparation method of the high dielectric voltage-resistant composite insulating film is further improved, in the (2), the process parameters of the magnetron sputtering are as follows: the sputtering base vacuum is lower than 1×10 -4 Pa, the sputtering parameter is 150W-200W, the Ar2 flow is 15sccm-25sccm, oxygen is supplemented during the sputtering process, and the oxygen flow is 2sccm-4sccm; the purity of the Al2O3 target is 99.99%.

[0013] The preparation method of the high dielectric voltage-resistant composite insulating film is further improved, in the (3), the process parameters of the magnetron sputtering are as follows: the sputtering base vacuum is lower than 1×10 -4 Pa, the sputtering parameter is 200W-250W, the Ar2 flow is 15sccm-25sccm, oxygen is supplemented during the sputtering process, and the oxygen flow is 4sccm-6sccm; the purity of the SiO2 target is 99.99%.

[0014] As a general technical concept, the application also provides a high dielectric voltage-resistant alloy thin film pressure-sensitive core, which comprises a substrate material, and an insulating layer, a functional material layer, a protective layer and an electrode layer are sequentially deposited on the surface of the substrate material, and the insulating layer is composed of a tantalum pentoxide film, an aluminum oxide film and a silicon oxide film which are sequentially stacked from bottom to top.

[0015] The high dielectric voltage-resistant alloy thin film pressure-sensitive core is further improved, the thickness of the tantalum pentoxide film is 50nm-150nm; the thickness of the aluminum oxide film is 375nm-450nm; and the thickness of the silicon oxide film is 2.5μm-3.5μm.

[0016] The high dielectric voltage-resistant alloy thin film pressure-sensitive core further improves the base material, which is 17-4PH stainless steel or 15-5PH stainless steel.

[0017] The high dielectric voltage-resistant alloy thin film pressure-sensitive core further improves the functional material layer, which is one of NiCr thin film, PdCr thin film, TaN thin film and TiON thin film; and the thickness of the functional material layer is 80nm-150nm.

[0018] The high dielectric voltage-resistant alloy thin film pressure-sensitive core further improves the protective layer, which is one of silicon oxide thin film, silicon nitride thin film and aluminum oxide thin film; and the thickness of the protective layer is 400nm-600nm.

[0019] The high dielectric voltage-resistant alloy thin film pressure-sensitive core further improves the electrode layer, which is one of Au electrode, Ni electrode, Cu electrode and Al electrode; and the thickness of the electrode layer is 0.8μm-1.2μm.

[0020] As a general technical concept, the application further provides a preparation method of the high dielectric voltage-resistant alloy thin film pressure-sensitive core.

[0021] S1, pretreating the base material;

[0022] S2, sequentially depositing an insulating layer and a functional material layer on the base material in the same vacuum cavity, specifically:

[0023] S2-1, depositing a tantalum pentoxide thin film on the base material by magnetron sputtering with a Ta2O5 target as a sputtering source;

[0024] S2-2, depositing an aluminum oxide thin film on the tantalum pentoxide thin film by magnetron sputtering with an Al2O3 target as a sputtering source;

[0025] S2-3, depositing a silicon oxide thin film on the aluminum oxide thin film by magnetron sputtering with a SiO2 target as a sputtering source to form the insulating layer;

[0026] S2-4, depositing a functional material thin film on the silicon oxide thin film by magnetron sputtering with a 6J22 target as a sputtering source, preparing a functional material layer pattern on the functional material thin film by a photolithography process, and etching the functional material thin film by a wet etching process to form the functional material layer;

[0027] S3, depositing an electrode layer on the functional material layer;

[0028] S4, depositing a protective layer on the functional material layer to complete the preparation of the high dielectric voltage-resistant alloy thin film piezoresistive core.

[0029] The preparation method of the high dielectric voltage-resistant alloy thin film piezoresistive core is further improved, in S2-1, the process parameters of the magnetron sputtering are as follows: the sputtering base vacuum is lower than 1×10 -4 Pa, the sputtering parameter is 100W-150W, the Ar2 flow is 15sccm, oxygen is supplemented during the sputtering process, and the oxygen flow is 2sccm-4sccm; the purity of the Ta2O5 target material is 99.99%.

[0030] The preparation method of the high dielectric voltage-resistant alloy thin film piezoresistive core is further improved, in S2-2, the process parameters of the magnetron sputtering are as follows: the sputtering base vacuum is lower than 1×10 -4 Pa, the sputtering parameter is 150W-200W, the Ar2 flow is 15sccm-25sccm, oxygen is supplemented during the sputtering process, and the oxygen flow is 2sccm-4sccm; the purity of the Al2O3 target material is 99.99%.

[0031] The preparation method of the high dielectric voltage-resistant alloy thin film piezoresistive core is further improved, in S2-3, the process parameters of the magnetron sputtering are as follows: the sputtering base vacuum is lower than 1×10 -4 Pa, the sputtering parameter is 200W-250W, the Ar2 flow is 15sccm-25sccm, oxygen is supplemented during the sputtering process, and the oxygen flow is 4sccm-6sccm; the purity of the SiO2 target material is 99.99%.

[0032] The preparation method of the high dielectric voltage-resistant alloy thin film piezoresistive core is further improved, in S2-4, the process parameters of the magnetron sputtering are as follows: the sputtering base vacuum is lower than 1×10 -4 Pa, the sputtering parameter is 100W-150W, the Ar2 flow is 15sccm-25sccm; the purity of the 6J22 target material is 99.99%.

[0033] The preparation method of the high dielectric voltage-resistant alloy thin film piezoresistive core is further improved, in S1, the pretreatment is as follows: the substrate material is ground by using alumina abrasive, the grinding time is 30min-60min, the substrate material is polished by using a silicon suspension, the polishing time is 30min-60min, ultrasonic cleaning is performed in acetone, alcohol, and deionized water in turn, each cleaning time is 10min-20min, and drying is performed at 80℃-120℃ for 10min-20min.

[0034] The preparation method of the high dielectric voltage-resistant alloy thin film pressure-sensitive core further improves the step S3, wherein a double ion beam sputtering process is used to deposit an electrode layer on the functional material layer, the process parameters of the double ion beam sputtering process are as follows: voltage 450V-550V and current 40mA-50mA, and the sputtering source of the electrode layer is an Au target material with a purity of 99.99%.

[0035] The preparation method of the high dielectric voltage-resistant alloy thin film pressure-sensitive core further improves the step S4, wherein a double ion beam sputtering process is used to deposit a protective layer on the functional material layer, the process parameters of the double ion beam sputtering process are as follows: voltage 450V-550V and current 50mA-60mA, and the sputtering source of the electrode layer is an SiO2 target material with a purity of 99.99%.

[0036] The preparation method of the high dielectric voltage-resistant alloy thin film pressure-sensitive core further improves the step S4, wherein after the deposition of the protective layer is completed, the method further comprises: performing heat treatment on the sample to obtain the high dielectric voltage-resistant alloy thin film pressure-sensitive core, the heat treatment is performed in a normal pressure environment, the temperature of the heat treatment is 350℃-400℃, and the time of the heat treatment is 35min-45min.

[0037] Compared with the prior art, the preparation method of the high dielectric voltage-resistant alloy thin film pressure-sensitive core has the following advantages:

[0038] (1) In view of the defects of the existing insulating layer for pressure sensors, such as insufficient dielectric voltage resistance and large film stress, the application creatively proposes a high dielectric voltage-resistant composite insulating film for pressure sensors, which comprises, from bottom to top, a tantalum pentoxide film, an aluminum oxide film and a silicon oxide film stacked in sequence, wherein the tantalum pentoxide film serves as a buffer layer to improve the adhesion of the film, the aluminum oxide film improves the dielectric voltage resistance, which can overcome the low dielectric voltage resistance of a single insulating film, and the silicon oxide film is the main body of the insulating material, and the thickness and film quality of the silicon oxide film directly determine the voltage resistance of the sensor, so that the composite insulating film composed of the tantalum pentoxide film, the aluminum oxide film and the silicon oxide film has excellent dielectric voltage resistance and small film stress, and is a new type of insulating film with excellent performance, which can be used as an insulating layer between the functional material layer and the base material of the pressure sensor, and is conducive to obtaining a pressure sensor with excellent performance, has high use value and good application prospect.

[0039] (2) In order to solve the problem that the existing insulation layer preparation method cannot prepare an insulation layer with good compactness and adhesion, the application creatively proposes a preparation method of a high dielectric voltage-resistant composite insulation film for a pressure sensor, in which a tantalum pentoxide film, an aluminum oxide film and a silicon oxide film are sequentially prepared by magnetron sputtering in the same vacuum chamber, thereby avoiding the problem of multiple in-and-out of the vacuum chamber during the preparation process, and thus a thin film with good compactness and adhesion can be prepared, which is beneficial to avoid the problems of film peeling and cracking caused by stress concentration.

[0040] (3) In order to solve the problem that the existing pressure sensor has a low dielectric voltage resistance, the application creatively proposes a high dielectric voltage-resistant alloy thin film pressure-sensitive core, which comprises a base material, and the surface of the base material is sequentially provided with an insulation layer, a functional material layer, a protective layer and an electrode layer, wherein the insulation layer is composed of a tantalum pentoxide film, an aluminum oxide film and a silicon oxide film stacked from bottom to top. Compared with conventional pressure sensors, in the application, the composite insulation film composed of the tantalum pentoxide film, the aluminum oxide film and the silicon oxide film stacked from bottom to top is used as the insulation layer, and since the composite insulation film has excellent dielectric voltage resistance performance, small film stress, good compactness and good adhesion, when it is arranged between the functional material layer and the base material as the insulation layer, the dielectric voltage resistance of the pressure sensor can be further improved to 875V, and at the same time, the alloy thin film pressure-sensitive core of the application has the advantages of high detection precision, high sensitivity and good reliability in harsh environments, and thus the high dielectric voltage-resistant alloy thin film pressure-sensitive core of the application, which uses the high dielectric voltage-resistant composite insulation film as the insulation layer, can meet the demand of special pressure monitoring for high-speed trains.

[0041] (4) In the high dielectric voltage-resistant alloy thin film pressure-sensitive core of the application, the thicknesses of the film layers in the insulation layer are optimized, the thickness of the tantalum pentoxide film is optimized to 50nm-150nm, the thickness of the aluminum oxide film is optimized to 375nm-450nm, and the thickness of the silicon oxide film is optimized to 2.5um-3.5um, which not only effectively reduces the cost, but also makes the insulation layer have higher dielectric voltage resistance and stronger adhesion and is not easy to crack, because if the tantalum pentoxide film is too thin, the adhesion of the film layer is poor, and if it is too thick, it has no practical significance and increases the overall process time and cost; at the same time, if the aluminum oxide film is too thin, it is not conducive to improving the dielectric voltage resistance, and if it is too thick, the internal stress of the film is too large and is prone to rupture in the later environmental test; in addition, if the silicon oxide film is too thin, the insulation and dielectric voltage resistance will be reduced, and if it is too thick, it cannot effectively improve the dielectric voltage resistance, but increases the process time.

[0042] (5) The application further provides a preparation method of the high dielectric voltage-resistant alloy thin film pressure-sensitive core, the five-tantalum pentoxide thin film, the aluminum oxide thin film and the silicon oxide thin film and the functional material layer are sequentially prepared in the same vacuum cavity through magnetron sputtering, the problem of entering and exiting the vacuum cavity for multiple times in the preparation process is avoided, and therefore the thin film with good compactness and adhesion can be prepared, the problems of thin film peeling and cracking caused by stress concentration are avoided, and the high dielectric voltage-resistant alloy thin film pressure-sensitive core prepared in this way has more excellent performance. BRIEF DESCRIPTION OF DRAWINGS

[0043] In order to make the purpose, technical scheme and advantages of the embodiments of the application clearer, the technical scheme in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application.

[0044] Figure 1 FIG. 1 is a sectional structure diagram of the high dielectric voltage-resistant alloy thin film pressure-sensitive core in the application.

[0045] Figure 2 FIG. 4 is a photomask pattern diagram for preparing the functional material layer in the application.

[0046] LEGEND:

[0047] 1, base material; 2, five-tantalum pentoxide thin film; 3, aluminum oxide thin film; 4, silicon oxide thin film; 5, functional material layer; 6, protective layer; 7, electrode layer. DETAILED DESCRIPTION

[0048] The application will be further described below in combination with the drawings of the specification and specific preferred embodiments, but the protection scope of the application is not limited in this way.

[0049] Embodiment 1

[0050] The existing insulating layer for the pressure sensor takes the silicon dioxide thin film as the insulating layer, and still has defects such as insufficient dielectric voltage-resistant performance and large thin film stress. Based on this, the application provides a high dielectric voltage-resistant composite insulating film for a pressure sensor, which comprises five-tantalum pentoxide thin films, aluminum oxide thin films and silicon oxide thin films stacked from bottom to top, wherein the five-tantalum pentoxide thin films serve as buffer layers to improve the adhesion of the thin films, the aluminum oxide thin films improve the dielectric voltage-resistant capability, can overcome the defect of low dielectric voltage-resistant capability of a single insulating thin film, and the silicon oxide thin films are the main body of the insulating material, and the thickness and the quality of the thin films directly determine the voltage-resistant capability of the sensor. Therefore, through reasonable collocation of the five-tantalum pentoxide thin films, the aluminum oxide thin films and the silicon oxide thin films, the composite insulating film composed of them has advantages such as excellent dielectric voltage-resistant performance and small thin film stress, is a novel insulating film with excellent performance, can be used as the insulating layer between the functional material layer and the base material of the pressure sensor, is conducive to obtaining, has high use value and good application prospect.

[0051] For better understanding of the innovation of the technical solutions of the present application, as one of the cases in the technical solutions of the present application, the high dielectric voltage-resistant composite insulating film involved includes, from bottom to top, a tantalum pentoxide film, an aluminum oxide film and a silicon oxide film stacked in sequence, wherein the thickness of the tantalum pentoxide film is 50 nm, the thickness of the aluminum oxide film is 375 nm, and the thickness of the silicon oxide film is 3.5 μm.

[0052] Further, a preparation method of the high dielectric voltage-resistant composite insulating film in the above embodiment is also provided, and the high dielectric voltage-resistant composite insulating film is prepared in the same vacuum cavity, and the preparation method includes the following steps:

[0053] (1) A tantalum pentoxide film is deposited on a pretreated substrate material (17-4PH stainless steel) by magnetron sputtering with a Ta2O5 target as a sputtering source, wherein the process parameters of the magnetron sputtering are as follows: the sputtering base vacuum is lower than 1×10 -4 Pa, the sputtering parameter is 150 W, the Ar2 flow rate is 15 sccm, oxygen is supplemented during the sputtering process, the oxygen flow rate is 2 sccm, and the purity of the Ta2O5 target is 99.99%.

[0054] (2) An aluminum oxide film is deposited on the tantalum pentoxide film by magnetron sputtering with an Al2O3 target as a sputtering source, wherein the process parameters of the magnetron sputtering are as follows: the sputtering base vacuum is lower than 1×10 -4 Pa, the sputtering parameter is 150 W, the Ar2 flow rate is 15 sccm, oxygen is supplemented during the sputtering process, the oxygen flow rate is 2 sccm, and the purity of the Al2O3 target is 99.99%.

[0055] (3) A silicon oxide film is deposited on the aluminum oxide film by magnetron sputtering with a SiO2 target as a sputtering source to obtain a high dielectric voltage-resistant composite insulating film, wherein the process parameters of the magnetron sputtering are as follows: the sputtering base vacuum is lower than 1×10 -4 Pa, the sputtering parameter is 200 W, the Ar2 flow rate is 15 sccm, oxygen is supplemented during the sputtering process, the oxygen flow rate is 4 sccm, and the purity of the SiO2 target is 99.99%.

[0056] Example 2

[0057] The existing pressure sensor takes silicon dioxide film as an insulation layer, and due to the defects of the insulation layer such as insufficient dielectric voltage resistance, large film stress, poor compactness and poor adhesion, the matching of the insulation layer with the substrate and the functional material layer is still insufficient, so that the pressure sensor still has defects such as insufficient dielectric voltage resistance, large film stress, low detection precision, low sensitivity and poor reliability in harsh environments. Based on this, the application provides a high dielectric voltage resistance alloy thin film pressure sensitive core, which comprises a substrate material, and the surface of the substrate material is sequentially provided with an insulation layer, a functional material layer, a protective layer and an electrode layer, wherein the insulation layer is a composite insulation film sequentially stacked from bottom to top by a tantalum pentoxide film, an aluminum oxide film and a silicon oxide film. Compared with the conventional pressure sensor, the composite insulation film sequentially stacked from bottom to top by the tantalum pentoxide film, the aluminum oxide film and the silicon oxide film is used as the insulation layer, and due to the excellent dielectric voltage resistance, small film stress, good compactness and good adhesion of the composite insulation film, when the composite insulation film is used as the insulation layer between the functional material layer and the substrate material, the dielectric voltage resistance of the pressure sensor can be further improved to 875V, and the alloy thin film pressure sensitive core of the application has the advantages of high detection precision, high sensitivity and good reliability in harsh environments. Therefore, the high dielectric voltage resistance alloy thin film pressure sensitive core of the application with the composite insulation film as the insulation layer can meet the demand of special pressure monitoring for high-speed trains.

[0058] In order to better understand the innovation of the technical scheme of the application, as one of the cases in the technical scheme of the application, the high dielectric voltage resistance alloy thin film pressure sensitive core comprises a substrate material 1, and the surface of the substrate material 1 is sequentially provided with an insulation layer, a functional material layer 5, a protective layer 6 and an electrode layer 7, wherein the insulation layer is a composite of a tantalum pentoxide film 3, an aluminum oxide film 4 and a silicon oxide film 5 stacked from bottom to top, wherein the thickness of the tantalum pentoxide film is 50 nm, the thickness of the aluminum oxide film is 375 nm, and the thickness of the silicon oxide film is 3.5 microns.

[0059] In this embodiment, the substrate material is 17-4PH stainless steel.

[0060] In this embodiment, the functional material layer is a NiCr film with a thickness of 150 nm.

[0061] In this embodiment, the protective layer is a silicon oxide film with a thickness of 400 nm.

[0062] In this embodiment, the electrode layer is deposited on the functional material layer, wherein the electrode layer is an Au electrode with a thickness of 1.2 microns.

[0063] Further, a preparation method of the high dielectric voltage resistance alloy thin film pressure sensitive core in the above embodiment is further provided, which comprises the following steps:

[0064] S1, pretreating the base material, specifically: using an aluminum oxide abrasive to grind the surface of the base material (17-4PH stainless steel) for 60 minutes, polishing the base material with a silicon oxide suspension (the average particle size of the silicon oxide particles in the suspension is 0.3 microns) for 60 minutes, sequentially ultrasonic cleaning with acetone, alcohol, and deionized water for 15 minutes each, and drying at 100°C for 20 minutes.

[0065] S2, placing the pretreated base material in a multi-target magnetron sputtering device (conventional device) and sequentially depositing an insulating layer and a functional material layer on the base material in the same vacuum chamber, specifically:

[0066] S2-1, using the radio frequency source 1 of the multi-target magnetron sputtering device to prepare a tantalum pentoxide film, using a 3-inch Ta2O5 target as the sputtering source for magnetron sputtering to deposit a tantalum pentoxide film on the pretreated base material, wherein the process parameters for magnetron sputtering are: a sputtering base vacuum of less than 1x10 -4 Pa, a sputtering parameter of 150W, an Ar2 flow rate of 15sccm, oxygen supplementation during sputtering with an oxygen flow rate of 2sccm, and a purity of the Ta2O5 target of 99.99%.

[0067] S2-2, closing the radio frequency source 1 of the multi-target magnetron sputtering device and opening the radio frequency source 2 to prepare an aluminum oxide film, using a 3-inch Al2O3 target as the sputtering source for magnetron sputtering to deposit an aluminum oxide film on the tantalum pentoxide film, wherein the process parameters for magnetron sputtering are: a sputtering base vacuum of less than 1x10 -4 Pa, a sputtering parameter of 150W, an Ar2 flow rate of 15sccm, oxygen supplementation during sputtering with an oxygen flow rate of 2sccm, and a purity of the Al2O3 target of 99.99%.

[0068] S2-3, closing the radio frequency source 2 of the multi-target magnetron sputtering device and opening the radio frequency sources 3 and 4 to prepare a silicon oxide film (using double-target co-sputtering to improve the film deposition rate), using a 3-inch SiO2 target as the sputtering source for magnetron sputtering to deposit a silicon oxide film on the aluminum oxide film to form an insulating layer, wherein the process parameters for magnetron sputtering are: a sputtering base vacuum of less than 1x10 - 4 Pa, a sputtering parameter of 200W, an Ar2 flow rate of 15sccm, oxygen supplementation during sputtering with an oxygen flow rate of 4sccm, and a purity of the SiO2 target of 99.99%.

[0069] S2-4. Turn off the RF source 3 of the multi-target magnetron sputtering equipment, and turn on the RF source 4 and DC source 5 to prepare a NiCr thin film. Use a 6J22 target as the sputtering source for magnetron sputtering to deposit a functional material thin film (NiCr thin film) on the silicon oxide thin film. Use photolithography and a photolithography plate 1 (the pattern of which is shown in the image) to perform the deposition. Figure 2 (As shown) A functional material layer pattern was prepared on a functional material thin film. The functional material thin film was etched using a wet etching process to form the functional material layer. The magnetron sputtering process parameters were: sputtering background vacuum below 1×10⁻⁶. -4 Pa, sputtering parameters 150W, Ar2 flow rate 15sccm, 6J22 target purity 99.99%.

[0070] S3. Deposit an electrode layer on the functional material layer. Specifically, an electrode layer (gold electrode) is deposited on the functional material layer using a photomask 2 (conventional photomask) and a dual-ion beam sputtering process. The process parameters of the dual-ion beam sputtering process are: voltage 500V, current 50mA, and the sputtering source of the electrode layer is an Au target with a purity of 99.99%.

[0071] S4. Deposit an electrode layer on the functional material layer, specifically by using photomask 3 (conventional photomask) and dual-ion beam sputtering to deposit an electrode layer (silicon oxide thin film) on the functional material layer.

[0072] S5. Heat treatment is performed on the sample in step S4. Specifically, the sample is placed in an annealing furnace and heated to 350°C for high-temperature annealing in an atmospheric pressure environment for 40 minutes. After cooling to room temperature in the furnace, the sample is taken out to obtain a high dielectric voltage-resistant alloy thin film varistor core.

[0073] Tests have shown that the dielectric withstand voltage of the dielectric withstand alloy thin film varistor core prepared in this embodiment is as high as 875V.

[0074] In summary, the high dielectric withstand voltage alloy thin film pressure-sensitive core of the present invention uses a composite insulating film consisting of a tantalum pentoxide thin film, an alumina thin film, and a silicon oxide thin film stacked sequentially from bottom to top as the insulating layer. Because this composite insulating film has excellent dielectric withstand voltage performance, low film stress, good density, and good adhesion, when used as an insulating layer between the functional material layer and the substrate material, it can further increase the dielectric withstand voltage of the pressure sensor to 875V, while the dielectric withstand voltage of conventional sensors is 500V. Simultaneously, this also gives the alloy thin film pressure-sensitive core of the present invention advantages such as high detection accuracy, high sensitivity, and good reliability in harsh environments. Therefore, the high dielectric withstand voltage alloy thin film pressure-sensitive core constructed with a high dielectric withstand voltage composite insulating film as the insulating layer of the present invention can meet the requirements of special pressure monitoring for high-speed trains.

[0075] The above examples are only preferred embodiments of the present application, and the protection scope of the present application is not limited to the above examples. Any technical scheme falling within the concept of the present application belongs to the protection scope of the present application. It should be pointed out that improvements and refinements made by those of ordinary skill in the art without departing from the principles of the present application should also be considered as falling within the protection scope of the present application.

Claims

1. A high dielectric voltage-resistant composite insulating film, characterized by, The high dielectric voltage-resistant composite insulating film comprises, from bottom to top, a tantalum pentoxide film, an aluminum oxide film and a silicon oxide film which are stacked in sequence; the thickness of the tantalum pentoxide film is 50-150 nm; the thickness of the aluminum oxide film is 375-450 nm; and the thickness of the silicon oxide film is 2.5-3.5 μm.

2. The method of producing a high dielectric voltage-resistant composite insulating film according to claim 1, characterized by, The high dielectric voltage-resistant composite insulating film is prepared in the same vacuum cavity, comprising the following steps: (1) depositing a tantalum pentoxide film on a base material by magnetron sputtering with a Ta2O5 target as a sputtering source; (2) depositing an aluminum oxide film on the tantalum pentoxide film by magnetron sputtering with an Al2O3 target as a sputtering source; (3) depositing a silicon oxide film on the aluminum oxide film by magnetron sputtering with a SiO2 target as a sputtering source to obtain the high dielectric voltage-resistant composite insulating film.

3. The method for producing a high dielectric voltage-resistant composite insulating film according to claim 2, characterized by, In the (1), the process parameters of the magnetron sputtering are as follows: the sputtering base vacuum is lower than 1×10 -4 Pa, the sputtering parameter is 100 W-150 W, the Ar2 flow is 15 sccm, the oxygen is supplemented during the sputtering process, the oxygen flow is 2 sccm-4 sccm; the purity of the Ta2O5 target material is 99.99%; In the (2), the process parameters of the magnetron sputtering are as follows: the sputtering base vacuum is lower than 1*10 -4 Pa, the sputtering parameter is 150 W-200 W, the Ar2 flow is 15 sccm-25 sccm, the oxygen is supplemented during the sputtering process, the oxygen flow is 2 sccm-4 sccm; the purity of the Al2O3 target material is 99.99%. In the (3), the process parameters of the magnetron sputtering are as follows: the sputtering base vacuum is lower than 1×10 -4 Pa, the sputtering parameter is 200 W-250 W, the Ar2 flow rate is 15 sccm-25 sccm, the oxygen is supplemented during the sputtering process, the oxygen flow rate is 4 sccm-6 sccm; and the purity of the SiO2 target material is 99.99%.

4. A high dielectric voltage-resistant alloy thin film pressure-sensitive core, comprising a base material, the surface of the base material sequentially deposited with an insulation layer, a functional material layer, a protective layer and an electrode layer, characterized in that, The insulating layer is composed of, from bottom to top, a tantalum pentoxide film, an aluminum oxide film and a silicon oxide film which are stacked in sequence; the thickness of the tantalum pentoxide film is 50-150 nm; the thickness of the aluminum oxide film is 375-450 nm; and the thickness of the silicon oxide film is 2.5-3.5 μm.

5. The high dielectric voltage-resistant alloy thin film pressure sensitive element according to claim 4, wherein The base material is 17-4PH stainless steel or 15-5PH stainless steel; The functional material layer is one of a NiCr film, a PdCr film, a TaN film and a TiON film; and the thickness of the functional material layer is 80-150 nm. The protective layer is one of a silicon oxide film, a silicon nitride film and an aluminum oxide film; and the thickness of the protective layer is 400-600 nm. The electrode layer is deposited on the functional material layer; the electrode layer is one of an Au electrode, a Ni electrode, a Cu electrode and an Al electrode; and the thickness of the electrode layer is 0.8-1.2 μm.

6. A method of producing a high dielectric voltage-resistant alloy thin film pressure sensitive element as claimed in claim 4 or 5, characterized by, The method comprises the following steps: S1, pretreating the base material; S2, sequentially depositing an insulating layer and a functional material layer on the base material in the same vacuum cavity, specifically: S2-1, depositing a tantalum pentoxide film on the base material by magnetron sputtering with a Ta2O5 target as a sputtering source; S2-2, depositing an aluminum oxide film on the tantalum pentoxide film by magnetron sputtering with an Al2O3 target as a sputtering source; S2-3, depositing a silicon oxide film on the aluminum oxide film by magnetron sputtering with a SiO2 target as a sputtering source to form the insulating layer; S2-4, depositing a functional material film on the silicon oxide film by magnetron sputtering with a 6J22 target as a sputtering source, preparing a functional material layer pattern on the functional material film by a photolithography process, and etching the functional material film by a wet etching process to form the functional material layer; S3, depositing an electrode layer on the functional material layer; S4, depositing a protective layer on the functional material layer to complete the preparation of the high dielectric voltage-resistant alloy thin film piezoelectric element.

7. The method for preparing the high dielectric withstand voltage alloy thin film varistor core according to claim 6, characterized in that, The process parameters of the magnetron sputtering in S2-1 are as follows: the sputtering background vacuum is lower than 1×10 -4 -4 sccm; the purity of the Ta2O5 target material is 99.99%; In the S2-2, the process parameters of the magnetron sputtering are as follows: the sputtering background vacuum is lower than 1×10 -4 Pa, the sputtering parameter is 150 W-200 W, the Ar2 flow rate is 15 sccm-25 sccm, oxygen is supplemented during the sputtering process, the oxygen flow rate is 2 sccm-4ccm; the purity of the Al2O3 target material is 99.99%. The process parameters of the magnetron sputtering in the S2-3 are as follows: the sputtering background vacuum is lower than 1×10 -4 Pa, the sputtering parameter is 200 W to 250 W, the Ar2 flow rate is 15 sccm to 25 sccm, oxygen is supplemented during the sputtering process, the oxygen flow rate is 4 sccm to 6 sccm, and the purity of the SiO2 target material is 99.99%. In the S2-4, the process parameters of the magnetron sputtering are as follows: the sputtering base vacuum is lower than 1×10 -4 , the sputtering parameter is 100W-150W, the Ar2 flow is 15sccm-25sccm; and the purity of the 6J22 target material is 99.99%.

8. The method for preparing a high dielectric withstand voltage alloy thin film varistor core according to claim 6 or 7, characterized in that, In the S1, the pretreatment is: grinding the base material by using alumina abrasive, the grinding time is 30-60 minutes, polishing the base material by using silica suspension, sequentially cleaning by using acetone, alcohol and deionized water, each cleaning time is 10-20 minutes, and drying at 80-120 DEG C for 10-20 minutes; In the S3, the electrode layer is deposited on the functional material layer by using double ion beam sputtering process, the process parameters of the double ion beam sputtering process are: voltage 450-550 V and current 40-50 mA, and the sputtering source of the electrode layer is Au target material with purity of 99.99%; In the S4, the protection layer is deposited on the functional material layer by using double ion beam sputtering process, the process parameters of the double ion beam sputtering process are: voltage 450-550 V and current 50-60 mA, and the sputtering source of the electrode layer is SiO2 target material with purity of 99.99%; In the S4, after the deposition of the protection layer, the sample is further subjected to heat treatment to obtain the high dielectric voltage-resistant alloy thin film piezoelectric element; The heat treatment is carried out in normal pressure environment, the temperature of the heat treatment is 350-400 DEG C, and the time of the heat treatment is 35-45 minutes.

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