CN118814113A - Ir-Hf alloy thin film - Google Patents

Abstract

The present invention provides an Ir-Hf alloy film, in which Hf atoms account for 10% to 50%, and the preparation method comprises the following steps: ultrasonically cleaning a substrate, drying it and fixing it on a substrate stage; placing high-purity metal targets Ir and Hf at two target positions, and adjusting the angle of the target relative to the center line perpendicular to the substrate stage and the vertical distance between the target and the substrate stage; evacuating the deposition chamber and then passing high-purity Ar gas, adjusting the working gas pressure, setting the sputtering power of the target, and pre-sputtering the target; then rotating the substrate stage and opening the substrate baffle for formal sputtering to obtain an Ir-Hf alloy film. The Ir-Hf alloy film obtained by the present invention using multi-target DC magnetron sputtering has controllable and uniform composition, good hardness, small surface roughness, good corrosion resistance and strong oxidation resistance.

Description

Ir-Hf alloy thin film

Technical Field

The invention belongs to the field of alloy materials, and in particular relates to an Ir-Hf alloy film.

Background Art

In recent years, China's aerospace industry has developed rapidly. With the acceleration of the development speed, the performance requirements for thermal protection materials in the field are getting higher and higher, especially for materials that can withstand high temperatures above 2000℃ under extreme working conditions. Alternative materials with a melting point higher than 2000℃ include ultra-high temperature ceramics (UHTCs), etc., but the preparation of ultra-high temperature ceramics is extremely difficult, the cost is extremely high, and the thermal shock resistance is poor. At present, ultra-high temperature superconducting materials containing boron and silicon are mainly used for thermal protection materials under supersonic speeds. The principle is that borosilicate glass will be formed during the oxidation process to block oxygen and fill defects. However, when boron oxide is at 1200℃ and silicon dioxide is at 1600℃, it will evaporate rapidly, causing the material to degrade and eventually fail. Although the melting points of some high-melting-point oxides (such as _ZrO2 , _HfO2 , etc.) can theoretically reach above 2000℃, they cannot block the diffusion of oxygen. Therefore, in order to block oxygen, the thickness of the above materials is usually designed to be several hundred microns. However, when the material thickness is too thick, it often leads to undesirable cracking and poor compatibility between different layers. Therefore, it is necessary to find a high-temperature, high-efficiency oxygen diffusion barrier material to solve this problem.

Iridium (Ir) has a high melting point (2440°C), excellent corrosion resistance and extremely low high-temperature oxygen permeability. Even in a high-temperature environment of 2280°C, it does not chemically react with carbon. Therefore, in the field of high-temperature protective coatings, the application rate of Ir is extremely high, especially when the ambient temperature is higher than 1800°C. And it has a high melting point and low oxygen permeability at temperatures of 2000-2200°C. It is difficult for oxygen to pass through Ir at high temperatures. Ir is currently the best oxygen diffusion barrier material. When the ambient temperature is >2000°C, Ir with a thickness of 1μm has a more excellent antioxidant capacity than _SiO2 with a thickness of 1mm. Therefore, Ir is extremely suitable as a high-temperature antioxidant protective material. It is widely used as a protective coating for high-temperature structural components, such as satellites, liquid rocket engines, and leading edges and noses of hypersonic aircraft.

However, when the pure Ir coating is heated to above 1100°C, Ir is easily oxidized to form IrO ₃ , _which is easy to sublimate and eventually cause the coating to fail. Therefore, it is necessary to modify Ir by adding elements. At present, Ir-based alloys Ir-M (M = Ti, Nb, Hf, Zr, Ta and V) have attracted much attention as new high-temperature materials due to their high melting point and excellent oxidation resistance. This coating is also called Ir alloy coating. Although the addition of elements has modified Ir to a certain extent, it still has not achieved the ideal effect in preventing Ir from volatilizing after oxidation and preventing the coating from failing.

Therefore, developing an Ir alloy coating with better performance has become an urgent problem to be solved.

Summary of the invention

In order to solve the above problems, the object of the present invention is to provide an Ir-Hf alloy film, which has strong oxidation resistance and can effectively reduce the volatilization of Ir in the alloy film and maintain the high temperature performance of the alloy film.

In order to achieve the above object, the present invention provides an Ir-Hf alloy film, wherein the Ir-Hf alloy film is composed of non-equiatomic ratios or equiatomic ratios; the chemical expression of the Ir-Hf alloy in the alloy film is Ir-aHf, wherein a represents the part of the atomic percentage of Hf without the percentage sign, and the value of a is 10-50;

The method for preparing the Ir-Hf alloy film comprises the following steps:

1) ultrasonically clean the substrate in anhydrous ethanol for 10 minutes to remove pollutants attached to the surface of the substrate, and then rinse the substrate with deionized water after ultrasonic cleaning;

2) Blow dry the cleaned substrate with compressed nitrogen to make its surface clean and free of water stains;

3) Fix the sputtering surface of the substrate upward on the substrate disk, fix the substrate disk on the substrate stage of the deposition chamber of the high vacuum magnetron sputtering coating equipment, and adjust the rotating substrate baffle to a position that completely covers the substrate;

4) placing Ir and Hf pure metal bulk targets respectively on two different DC target positions in the deposition chamber, and adjusting the angle of the target relative to the center line perpendicular to the substrate stage and the vertical distance between the target and the substrate stage;

5) first use a mechanical pump to evacuate the deposition chamber to less than 5.0 Pa, and then use a molecular pump to evacuate the deposition chamber to less than 1.0×10 ^-2 Pa;

6) Ar gas is introduced into the deposition chamber, the working gas pressure is adjusted to 0.7-0.8 Pa, the DC constant current power supply of the corresponding target is turned on, the target sputtering power is set, and the target is pre-sputtered for 10-15 minutes to remove impurities on the surface of the target; wherein the sputtering power of the Ir target is 150 W, and the sputtering power of the Hf target is 50-250 W;

7) Setting the substrate stage rotation rate to 10-30 r/min, opening the substrate baffle and then performing thin film sputtering on the sputtering surface of the substrate for 30-60 min to obtain a thin film;

8) After the sputtering is completed, turn off the DC constant current power supply, turn off the Ar gas source, turn off the substrate rotation, and let the film cool to room temperature under vacuum and then take it out to obtain the Ir-Hf alloy film on the substrate.

As described above, in step 1), the sputtering surface of the substrate is polished with a damping cloth before ultrasonic cleaning.

As mentioned above, the substrate in step 1) is a single crystal Si wafer.

Preferably, the single crystal Si wafer is of P type, and its crystal orientation is <100>.

As mentioned above, the ultrasonic frequency in step 1) is 60-80 Hz.

As mentioned above, the Ir and Hf targets in step 4) are both pure metal blocks with a purity greater than or equal to 99.95%, a diameter of 60 mm, and a thickness of 3 to 5 mm.

As mentioned above, the angle of the target material in step 4) relative to the center line perpendicular to the substrate stage is 30°; the vertical distance between the pure metal block target material of Ir and Hf and the substrate stage is 10 cm.

Under the condition that other preparation parameters are the same, the angle will affect the deposition rate of the film. Too small or too large an angle will affect the thickness of the film. When the angle is 30°, the projected area of the target relative to the substrate is relatively large, the deposition rate is relatively fast, and the efficiency is high.

As mentioned above, in step 6), the flow rate of Ar gas is 40 sccm, and the purity is greater than or equal to 99.999%.

Regarding the sputtering power, when the sputtering power is lower than the required one, the target material is not easy to ignite, while when the sputtering power is higher than the required one, it is easy to cause the equipment to overheat and affect the sputtering effect.

As described above, the Ir-Hf alloy film obtained in step 8) is a single-phase face-centered cubic solid solution structure, a mixed structure of a single-phase face-centered cubic solid solution structure and an amorphous structure, or an amorphous structure.

As described above, the surface roughness of the Ir-Hf alloy film obtained in step 8) is 0.71-2.48 nm, the hardness of the film is 12-19 GPa, the elastic modulus is 200-380 GPa, and the oxidation rate of Ir in the film at 1300°C is 0.25-2.65 μm/h.

The advantages of the present invention are:

1. The Ir-Hf alloy film provided by the present invention is prepared by multi-target DC magnetron sputtering technology, that is, multiple targets are co-sputtered, and the target material is a pure metal target. This method can avoid the complicated target material preparation process, and alloy films with various chemical compositions can be prepared by changing the target material power or the atomic ratio of each element in a specific target material. This method has the characteristics of high deposition rate, wide material applicability, good repeatability, etc. Pure metal target materials are used in the preparation process of the present invention, and the raw materials are simple and easy to obtain, which is suitable for large-scale industrial production.

2. The present invention adjusts the sputtering power of Ir to 150w to obtain a (111) oriented solid solution structure, wherein the (111) orientation improves the oxidation resistance, and the solid solution structure improves the hardness. In the prior art, the structure of Ir is mostly a (220) oriented structure, which has lower oxidation resistance than the (111) oriented structure, and even by adding element modification, the oxidation resistance of Ir cannot be improved. The present invention also obtains Ir-Hf alloy films with different atomic ratios by adjusting the power of Hf. When the atomic percentage of Hf is less than 30%, the film has a single-phase substitution solid solution structure, the oxidation resistance of the film is significantly improved, and the volatilization rate of Ir in the film can be as low as 0.25μm/h, the hardness can reach up to 19GPa, the wear resistance is significantly enhanced, and the surface roughness is as low as 0.71nm; when the atomic percentage of Hf is greater than or equal to 30%, the film begins to transform from a solid solution to an amorphous structure, realizing a mixed structure of solid solution and amorphous structure, the plastic toughness of the mixed structure is significantly improved, the elastic modulus is 200GPa, and the corrosion resistance is significantly enhanced. And whether it is a single-phase substitution solid solution structure, a mixed structure of solid solution and amorphous structure, or an amorphous structure, the toughness of the Ir-Hf alloy film is improved, and the multiple effects of high hardness, oxidation resistance and corrosion resistance are achieved at the same time. The prepared Ir-Hf alloy film has uniform distribution of component elements and fine grains.

3. The Ir-Hf alloy film prepared by the present invention increases the volatilization temperature of pure Ir from 1100°C to 200-300°C, and reduces the volatilization rate of Ir in the film to 0.25 μm/h, which is much lower than the pure iridium and iridium alloy coatings prepared by the prior art.

4. The Ir-Hf alloy film prepared by the present invention breaks through the limitation of poor orientation of the film (220) prepared by traditional arc melting, molten salt electrodeposition, double glow plasma deposition and other technologies, and the chemical composition of the prepared film is evenly distributed, overcoming the disadvantage of uneven distribution of the Ir-Hf modified alloy structure prepared by traditional arc melting.

5. The thickness of the Ir-Hf alloy film prepared by the present invention is about 1 μm, but the anti-oxidation effect is better than that of 1 mm thick _SiO2 . The thickness of other existing Ir alloy films is mostly tens of μm. Due to the high cost of Ir metal, reducing the thickness of the alloy film reduces the quality of the film on the one hand, and greatly reduces the production cost on the other hand.

6. The difference between the atomic radius of Ir and Hf is greater than 12%, which is more conducive to the preparation of amorphous Ir-Hf coating, improving the overall plasticity and toughness, improving the wear resistance of the film, and improving the corrosion resistance of the film.

7. Different from the traditional Ir-Hf alloy, the Ir-Hf film prepared by the present invention can precipitate HfO ₂ in situ during the oxidation process, which acts as an oxygen barrier to prevent oxygen from diffusing into the film, thereby greatly improving the oxidation resistance of the film and greatly reducing the volatilization rate of Ir in the film.

The beneficial effects of the present invention are:

The invention provides an Ir-Hf alloy film. The Ir-Hf alloy film is a binary alloy film prepared by a multi-target DC magnetron sputtering technology. The structure is a single-phase face-centered cubic solid solution structure, a mixed structure of a solid solution and an amorphous structure, or an amorphous structure. The surface roughness of the alloy film is 0.71-2.48 nm, the hardness of the film is 12-19 GPa, the elastic modulus is 200-380 GPa, and the oxidation rate of Ir in the film at a temperature of 1300° C. is as low as 0.25 μm/h. The alloy film has a wider application prospect.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a surface scanning EDS graph of the elements of the Ir-10Hf alloy film in Example 1 of the present invention.

FIG. 2 is an AFM image of the surface morphology of the Ir-10Hf alloy film in Example 1 of the present invention.

FIG. 3 is an XRD diagram of the Ir-10Hf alloy film in Example 1 of the present invention.

FIG. 4 is a surface scanning EDS image of the cross section of the oxidized Ir-10Hf alloy film in Example 1 of the present invention.

FIG. 5 is a surface scanning EDS image of the elements of the Ir-20Hf alloy film in Example 2 of the present invention.

FIG. 6 is an AFM image of the surface morphology of the Ir-20Hf alloy film in Example 2 of the present invention.

FIG. 7 is an XRD diagram of the Ir-20Hf alloy film in Example 2 of the present invention.

FIG8 is a surface scanning EDS image of the cross section of the oxidized Ir-20Hf alloy film in Example 2 of the present invention.

FIG. 9 is a surface scanning EDS image of the Ir-50Hf alloy film in Example 3 of the present invention.

FIG. 10 is an AFM image of the surface morphology of the Ir-50Hf alloy film in Example 3 of the present invention.

FIG. 11 is an XRD diagram of the Ir-50Hf alloy film in Example 3 of the present invention.

FIG. 12 is a surface scanning EDS image of the cross section of the oxidized Ir-50Hf alloy film in Example 3 of the present invention.

DETAILED DESCRIPTION

The following embodiments are used to provide a detailed and complete description of the present invention so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention, but are not used to limit the scope of the present invention.

Magnetron sputtering has the characteristics of high deposition rate, good film quality, controllable performance, and good bonding strength with the substrate, making it one of the most common methods for preparing thin films. Magnetron sputtering deposition most often uses single-target sputtering, that is, the sputtering target is a single alloy target. This technology can achieve precise control of the stoichiometric ratio of film components; but its disadvantage is that the preparation of alloy targets is complicated and costly. With the continuous improvement of the preparation technology level, multi-target magnetron sputtering process has been increasingly applied to the preparation research of multi-principal thin films. Multi-target magnetron sputtering uses multiple pure metal targets or binary alloy targets, which can effectively avoid the complex preparation process of a single alloy target; and by changing the target power, adjusting the sputtering order of different targets and the angle of the target relative to the substrate, a film with diversified components can be prepared, making the film preparation more flexible and conducive to high-throughput screening of film composition and performance.

The raw materials used in the following examples can all be purchased commercially:

1. The high-purity argon gas used in the present invention is purchased from Beijing Qianxi Jingcheng Gas Co., Ltd., with a purity greater than or equal to 99.999%

2. The Ir and Hf pure metal targets used in the thin film prepared by the present invention are both commercially available products with a purity greater than or equal to 99.95%, and single crystal Si is a commercially available commodity.

3. The high vacuum magnetron sputtering coating equipment used for the thin film prepared by the present invention is a multi-target high vacuum magnetron sputtering coating machine produced by Shenyang Oute Vacuum Technology Co., Ltd.; the mechanical pump and molecular pump are both supporting equipment of the high vacuum magnetron sputtering coating equipment produced by the same company.

Example 1 Preparation of Ir-10Hf Alloy Thin Film

A single crystal Si wafer of P type, crystal orientation <100>, and pre-damped and polished was ultrasonically cleaned with anhydrous ethanol at a frequency of 60 Hz for 10 minutes to remove pollutants attached to the surface of the substrate, and then the substrate was rinsed with deionized water after ultrasonic cleaning, and then blown dry with compressed nitrogen to make its surface clean and free of water stains; the single crystal Si wafer was fixed on a substrate disk, and the substrate disk was fixed on a substrate stage in a deposition chamber of a high vacuum magnetron sputtering coating equipment, and the rotating substrate baffle was adjusted to a position that completely covered the substrate; high-purity metal targets Ir and Hf were respectively placed on two different DC target positions in the deposition chamber, and the angles of the targets relative to the center line perpendicular to the substrate stage were adjusted to 30°, and the vertical distance between the targets and the substrate stage was adjusted to 10 cm; the deposition chamber was first evacuated to less than 5.0 Pa using a mechanical pump, and then the deposition chamber was evacuated to less than 1.0×10 ^-2 using a molecular pump Pa; high-purity Ar gas with a purity greater than or equal to 99.999% at a flow rate of 40sccm is introduced into the deposition chamber, the working gas pressure is adjusted to 0.8Pa, the power of the Ir target is set to 150W, the power of the Hf target is set to 50W, and the target is pre-sputtered for 10 minutes to remove impurities on the surface of the target; after the pre-sputtering is completed, the substrate rotation rate is set to 30r/min, the substrate baffle is opened, and formal sputtering is started for 50 minutes; after the sputtering is completed, the DC constant current power supply is turned off, the Ar gas source is turned off, the substrate rotation is turned off, the film is cooled to room temperature in a vacuum state, and then taken out to obtain the Ir-10Hf alloy film on the single crystal Si wafer.

Since the performance of the alloy film needs to be tested, and the single crystal Si wafer has only one crystal grain, the surface carrying the film has one crystal orientation, which can ensure that the properties of all places on this surface are the same and stable. At the same time, the single crystal Si wafer is convenient for later sample preparation and cutting. Therefore, in this embodiment and subsequent embodiments, a single crystal Si wafer is selected to carry the film. In actual applications, different substrates can be selected to carry the film according to needs.

Different substrate products are either polished or unpolished when purchased. For example, unpolished products need to be polished to increase the bonding strength between the film and the substrate. In this embodiment, since the film performance needs to be tested, polishing is performed before use to prevent the separation of the film and the substrate and increase the bonding strength between the two. To ensure the consistency of the experimental process, the subsequent embodiments also perform polishing.

Since the faster the substrate rotation speed, the greater the pressure on the equipment motor and the easier it is to damage, a lower substrate rotation speed is used in this embodiment, and preliminary experiments show that the substrate rotation speed has no substantial effect on the preparation and performance of the alloy film. In order to maintain consistent conditions, the same substrate rotation speed is also used in subsequent embodiments.

The experiment found that the sputtering time has no effect on the alloy composition, but affects the thickness of the film. In this embodiment, sputtering for 50 minutes just obtains a film with a thickness of about 1 μm, which is suitable for the performance test of subsequent samples. The same sputtering time is also used in the following embodiments to facilitate the performance test of the samples. In practical applications, different sputtering times can be selected according to different film thicknesses.

The chemical composition of the multi-principal alloy film was analyzed using an Oxford X-act energy dispersive spectrometer (EDS, installed on a scanning electron microscope). The element surface scanning EDS spectrum of the multi-principal alloy film is shown in Figure 1; wherein a) in Figure 1 is the surface morphology of the sample; b) is the distribution spectrum of the Ir element in the sample, and c) is the distribution spectrum of the Hf element in the sample. According to the quantitative calculation results of the software, the composition of the alloy film is Ir-10Hf.

The surface morphology of the Ir-10Hf alloy film was photographed using a Dimension ICON atomic force microscope (AFM) from Bruker GmbH of Germany. The tapping mode was used with a scanning area of 2μm×2um. The surface roughness (Ra) of the film was analyzed using NanoScope Analysis software. The results are shown in Figure 2: The surface AFM morphology of the Ir-10Hf multi-principal element alloy film is a needle-like structure with a surface roughness of 0.71nm.

The surface roughness of the film will affect the wear resistance of the film, where Ra < 1nm is an ultra-smooth surface and Ra < 10nm is a smooth surface. The friction coefficient and wear rate of the film generally increase with the increase of surface roughness. This is because the rough surface has a smaller contact area and higher contact pressure, which will lead to a higher friction coefficient and wear loss. Therefore, a smaller surface roughness is conducive to improving the wear resistance of the film.

The XRD phase analysis of Ir-10Hf alloy film was carried out by using D8 Advance X-ray diffractometer (XRD) of BRUKER AXS GmbH, Germany. The working voltage was 40kV, the working current was 40mA, the X-ray source was Cu-Ka (λ＝0.15418nm) ray, the grazing incidence angle was 1°, the scanning speed was 4°/min, the scanning step was 0.02°/step, and the scanning range was 10°～90°. The results are shown in Figure 3: According to the lattice diffraction extinction law, it can be determined that the three diffraction peaks marked in the spectrum correspond to the (111), (200), (220) and (311) crystal planes of the FCC structure phase, indicating that the crystal structure of the Ir-10Hf alloy film is a face-centered cubic (FCC) solid solution structure.

Since the film is a micro-nanoscale material, its hardness can only be measured using a nanoindenter. Vickers hardness and Rockwell hardness are usually used to measure the hardness of alloy blocks, but cannot be used to measure the hardness of films. Therefore, the Nano Indenter G200 nanoindenter produced by Agilent Technologies was used to test the hardness of the Ir-10Hf alloy film using the continuous stiffness mode. The results showed that the nanoindentation hardness value of the Ir-10Hf alloy film was as high as 19GPa, which can be used in high-hardness wear-resistant fields.

An isothermal oxidation experiment was conducted on the alloy film. The alloy film was placed in a muffle furnace at 1300°C for oxidation for 15 minutes, then taken out and cooled, and then scanned by EDS to calculate the oxidation volatilization rate of Ir in the film. As shown in Figure 4; where a) in Figure 4 is the cross-sectional morphology of the sample after oxidation, corresponding to the original thickness of the sample; b) is the distribution spectrum of the Ir element in the sample after oxidation. The volatilization thickness of the Ir element is calculated to obtain the volatilization rate of the Ir element. As can be seen from Figure 4, the distribution of the Ir element after oxidation for 15 minutes is obtained by EDS scanning analysis, and the volatilization rate of the Ir element is calculated to be 0.25μm/h.

Example 2 Preparation of Ir-20Hf alloy film

A single crystal Si wafer of P type, crystal orientation <100>, and pre-damped and polished was ultrasonically cleaned with anhydrous ethanol at a frequency of 60 Hz for 10 minutes to remove pollutants attached to the surface of the substrate, and then the substrate was rinsed with deionized water after ultrasonic cleaning, and then blown dry with compressed nitrogen to make its surface clean and free of water stains; the single crystal Si wafer was fixed on a substrate disk, and the substrate disk was fixed on a substrate stage in a deposition chamber of a high vacuum magnetron sputtering coating equipment, and the rotating substrate baffle was adjusted to a position that completely covered the substrate; high-purity metal targets Ir and Hf were respectively placed on two different DC target positions in the deposition chamber, and the angles of the targets relative to the center line perpendicular to the substrate stage were adjusted to 30°, and the vertical distance between the targets and the substrate stage was adjusted to 10 cm; the deposition chamber was first evacuated to less than 5.0 Pa using a mechanical pump, and then the deposition chamber was evacuated to less than 1.0×10 ^-2 using a molecular pump Pa; high-purity Ar gas with a purity greater than or equal to 99.999% at a flow rate of 40sccm is introduced into the deposition chamber, the working gas pressure is adjusted to 0.8Pa, the power of the Ir target is set to 150W, the power of the Hf target is set to 85W, and the target is pre-sputtered for 10 minutes to remove impurities on the surface of the target; after the pre-sputtering is completed, the substrate rotation rate is set to 30r/min, the substrate baffle is opened, and formal sputtering for 45 minutes is started; after the sputtering is completed, the DC constant current power supply is turned off, the Ar gas source is turned off, the substrate rotation is turned off, the film is cooled to room temperature in a vacuum state and then taken out to obtain the Ir-20Hf alloy film on the single crystal Si wafer.

The chemical composition of the multi-principal alloy film was analyzed using an Oxford X-act energy dispersive spectrometer (EDS, installed on a scanning electron microscope). The element surface scanning EDS spectrum of the multi-principal alloy film is shown in Figure 5; wherein a) in Figure 5 is the surface morphology of the sample; b) is the distribution spectrum of the Ir element in the sample, and c) is the distribution spectrum of the Hf element in the sample. According to the quantitative calculation results of the software, the composition of the alloy film is Ir-20Hf.

The surface morphology of the Ir-20Hf alloy film was photographed using a Dimension ICON atomic force microscope (AFM) from Bruker GmbH, Germany. The tapping mode was used and the scanning area was 2μm×2um. The surface roughness (Ra) of the film was analyzed using NanoScope Analysis software. The results are shown in Figure 6: The surface AFM morphology of the Ir-20Hf multi-principal alloy film is a needle-like structure with a surface roughness of 1.03nm.

The XRD phase analysis of Ir-10Hf alloy film was carried out by using D8 Advance X-ray diffractometer (XRD) of BRUKER AXS GmbH, Germany. The working voltage was 40kV, the working current was 40mA, the X-ray source was Cu-Ka (λ＝0.15418nm) ray, the grazing incidence angle was 1°, the scanning speed was 4°/min, the scanning step was 0.02°/step, and the scanning range was 10°～90°. The results are shown in Figure 7: According to the lattice diffraction extinction law, it can be determined that the three diffraction peaks marked in the spectrum correspond to the (111), (200), (220) and (311) crystal planes of the FCC structure phase, indicating that the crystal structure of Ir-20Hf alloy film is a face-centered cubic (FCC) solid solution structure.

The hardness of the Ir-20Hf alloy film was tested using the Nano Indenter G200 nanoindenter produced by Agilent Technologies in continuous stiffness mode. The results showed that the nanoindentation hardness value of the Ir-20Hf alloy film was 13 GPa, which can be used in high hardness and wear-resistant fields.

An isothermal oxidation experiment was conducted on the alloy film. The alloy film was placed in a muffle furnace at 1300°C for oxidation for 15 minutes, then taken out and cooled, and then scanned by EDS to calculate the oxidation volatilization rate of Ir in the film. As shown in Figure 8, a) in Figure 8 is the cross-sectional morphology of the sample after oxidation, corresponding to the original thickness of the sample; b) is the distribution spectrum of the Ir element in the sample after oxidation. The volatilization thickness of the Ir element is calculated to obtain the volatilization rate of the Ir element. As can be seen from Figure 8, the distribution of the Ir element after oxidation for 15 minutes is obtained by EDS scanning analysis, and the volatilization rate of the Ir element is calculated to be 0.85μm/h.

Example 3 Preparation of Ir-50Hf alloy film

A single crystal Si wafer of P type, crystal orientation <100>, and pre-damped and polished was ultrasonically cleaned with anhydrous ethanol at a frequency of 60 Hz for 10 minutes to remove pollutants attached to the surface of the substrate, and then the substrate was rinsed with deionized water after ultrasonic cleaning, and then blown dry with compressed nitrogen to make its surface clean and free of water stains; the single crystal Si wafer was fixed on a substrate disk, and the substrate disk was fixed on a substrate stage in a deposition chamber of a high vacuum magnetron sputtering coating equipment, and the rotating substrate baffle was adjusted to a position that completely covered the substrate; high-purity metal targets Ir and Hf were respectively placed on two different DC target positions in the deposition chamber, and the angles of the targets relative to the center line perpendicular to the substrate stage were adjusted to 30°, and the vertical distance between the targets and the substrate stage was adjusted to 10 cm; the deposition chamber was first evacuated to less than 5.0 Pa using a mechanical pump, and then the deposition chamber was evacuated to less than 1.0×10 ^-2 using a molecular pump Pa; high-purity Ar gas with a purity greater than or equal to 99.999% at a flow rate of 40sccm is introduced into the deposition chamber, the working gas pressure is adjusted to 0.8Pa, the power of the Ir target is set to 150W, the power of the Hf target is set to 250W, and the target is pre-sputtered for 10 minutes to remove impurities on the surface of the target; after the pre-sputtering is completed, the substrate rotation rate is set to 30r/min, the substrate baffle is opened, and formal sputtering begins for 30 minutes; after the sputtering is completed, the DC constant current power supply is turned off, the Ar gas source is turned off, the substrate rotation is turned off, the film is cooled to room temperature in a vacuum state, and then taken out to obtain the Ir-50Hf alloy film on the single crystal Si wafer.

The chemical composition of the multi-principal alloy film was analyzed using an Oxford X-act energy dispersive spectrometer (EDS, installed on a scanning electron microscope). The element surface scanning EDS spectrum of the multi-principal alloy film is shown in Figure 9; wherein a) in Figure 9 is the surface morphology of the sample; b) is the distribution spectrum of the Ir element in the sample, and c) is the distribution spectrum of the Hf element in the sample. According to the quantitative calculation results of the software, the composition of the alloy film is Ir-50Hf.

The surface morphology of the Ir-50Hf alloy film was photographed using a Dimension ICON atomic force microscope (AFM) from Bruker GmbH, Germany. The tapping mode was used and the scanning area was 2μm×2um. The surface roughness (Ra) of the film was analyzed using NanoScope Analysis software. The results are shown in Figure 10: The surface AFM morphology of the Ir-50Hf multi-principal alloy film is a needle-like structure with a surface roughness of 0.79nm.

The D8 Advance X-ray diffractometer (XRD) of BRUKER AXS GmbH, Germany, was used to perform XRD phase analysis on the Ir-50Hf alloy film. The operating voltage was 40 kV, the operating current was 40 mA, the X-ray source was Cu-Ka (λ = 0.15418 nm) rays, the grazing incidence angle was 1°, the scanning speed was 4°/min, the scanning step was 0.02°/step, and the scanning range was 10° to 90°. The results are shown in Figure 11: It can be determined that the Ir-50Hf alloy film is an amorphous structure.

The hardness of the Ir-50Hf alloy film was tested using the Nano Indenter G200 nanoindenter produced by Agilent Technologies in continuous stiffness mode. The results showed that the nanoindentation hardness value of the Ir-50Hf alloy film was as high as 14 GPa, which can be used in high hardness and wear-resistant fields.

An isothermal oxidation experiment was conducted on the alloy film. The alloy film was placed in a muffle furnace at 1300°C for oxidation for 15 minutes, then taken out and cooled, and then scanned by EDS to calculate the oxidation volatilization rate of Ir in the film. As shown in Figure 12, a) in Figure 12 is the cross-sectional morphology of the sample after oxidation, corresponding to the original thickness of the sample; b) is the distribution spectrum of the Ir element in the sample after oxidation. The volatilization thickness of the Ir element is calculated to obtain the volatilization rate of the Ir element. As can be seen from Figure 12, the distribution of the Ir element after oxidation for 15 minutes is obtained by EDS scanning analysis, and the volatilization rate of the Ir element is calculated to be 2.65μm/h.

It can be seen from the above embodiments that the present invention provides an Ir-Hf alloy film, which is made by multi-target DC magnetron sputtering technology. The obtained film hardness can reach 12GPa to 19GPa, and the surface roughness can reach the mirror level, which effectively enhances the wear resistance of the film. The in-situ precipitation of _HfO2 makes the volatilization rate of Ir in the film extremely low, which can reach as low as 0.25μm/h, greatly improving the oxidation resistance. As the Hf content increases, the film changes from a single-phase face-centered cubic solid solution to an amorphous structure, which improves the corrosion resistance of the film.

The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention shall be equivalent replacement methods and shall be included in the protection scope of the present invention.

Claims (10)

1. The Ir-Hf alloy thin film is characterized by comprising non-equal atomic ratio or equal atomic ratio; the chemical expression of the Ir-Hf alloy in the alloy film is Ir-aHf, wherein a represents the part with the percentage number removed in the atomic percentage of Hf, and the value of a is 10-50;

the preparation method of the Ir-Hf alloy film comprises the following steps:

1) Placing the substrate in absolute ethyl alcohol for ultrasonic cleaning for 10 minutes, removing pollutants attached to the surface of the substrate, and washing the substrate cleanly by deionized water after ultrasonic cleaning;

2) Drying the cleaned substrate by compressed nitrogen to ensure that the surface of the substrate is clean and free of water stains;

3) The sputtering face of the substrate is upwards fixed on a substrate disc, the substrate disc is fixed on a substrate table of a deposition chamber of high-vacuum magnetron sputtering coating equipment, and a rotary substrate baffle is adjusted to a position for completely covering the substrate;

4) Respectively preventing Ir and Hf pure metal block targets from being arranged on 2 different direct current targets of a deposition chamber, and adjusting the angle of the targets relative to the central line perpendicular to the substrate table and the vertical distance between the targets and the substrate table;

5) Firstly, vacuumizing a deposition chamber to be less than 5.0Pa by adopting a mechanical pump, and then vacuumizing the deposition chamber to be less than 1.0 multiplied by 10 ^-2 Pa by adopting a molecular pump;

6) Ar gas is introduced into the deposition chamber, the working pressure is regulated to be 0.7-0.8 Pa, a direct current constant current power supply of the corresponding target is turned on, the sputtering power of the target is set, and the target is subjected to pre-sputtering for 10-15 min to remove impurities on the surface of the target; wherein, the sputtering power of the Ir target is 150W, and the sputtering power of the Hf target is 50-250W;

7) Setting the rotation speed of the substrate table to be 10-30 r/min, opening the substrate baffle, and then sputtering a film on the sputtering surface of the substrate for 30-60 min to obtain the film;

8) And after sputtering, turning off a direct current constant current power supply, turning off an Ar gas source, turning off a substrate, cooling the film to room temperature in a vacuum state, and taking out the film to obtain the Ir-Hf alloy film on the substrate.

2. The Ir-Hf alloy thin film according to claim 1, further comprising: and 1) polishing the sputtering surface of the substrate by adopting damping cloth before ultrasonic cleaning.

3. The Ir-Hf alloy thin film according to claim 1, wherein the substrate is a single crystal Si wafer.

4. The Ir-Hf alloy thin film according to claim 3, wherein the single crystal Si sheet is P-type with a crystal orientation <100>.

5. The Ir-Hf alloy thin film according to claim 1, characterized in that the ultrasonic frequency in step 1) is 60-80 Hz.

6. The Ir-Hf alloy thin film according to claim 1, characterized in that the targets of Ir and Hf in step 4) are pure metal blocks, the purity is greater than or equal to 99.95%, the diameter is 60mm, and the thickness is 3-5 mm.

7. The Ir-Hf alloy thin film according to claim 1, wherein the angle of the target in step 4) with respect to the center line perpendicular to the substrate table is 30 °; the vertical distance between the pure metal block targets of Ir and Hf and the substrate table is 10cm.

8. The Ir-Hf alloy thin film according to claim 1, wherein the Ar gas flow rate in step 6) is 40sccm and the purity is 99.999% or more.

9. The Ir-Hf alloy thin film according to claim 1, wherein the Ir-Hf alloy thin film obtained in step 8) is a single-phase face-centered cubic solid solution structure, a mixed structure of a single-phase face-centered cubic solid solution structure and an amorphous structure, or an amorphous structure.

10. The Ir-Hf alloy thin film according to claim 1, characterized in that the surface roughness of the Ir-Hf alloy thin film obtained in step 8) is 0.71-2.48 nm, the hardness of the thin film is 12-19 GPa, the elastic modulus is 200-380 GPa, and the oxidation rate of Ir in the thin film at 1300 ℃ is 0.25-2.65 μm/h.