An Ir-Hf alloy thin film

Abstract

This invention provides an Ir-Hf alloy thin film, in which the Hf atomic ratio is 10% to 50%. The preparation method includes the following steps: ultrasonically cleaning, drying, and fixing the substrate 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 introducing 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 the Ir-Hf alloy thin film. The Ir-Hf alloy thin film obtained by multi-target DC magnetron sputtering of this invention has controllable and uniform composition, good hardness, low surface roughness, good corrosion resistance, and strong oxidation resistance.

Description

Technical Field

[0001] This invention belongs to the field of alloy materials, specifically relating to an Ir-Hf alloy thin film. Background Technology

[0002] In recent years, my country's aerospace industry has developed rapidly. With this accelerated development, the performance requirements for thermal protection materials have become increasingly stringent, especially for materials capable of withstanding temperatures above 2000℃ under extreme operating conditions. Materials with melting points above 2000℃ include ultra-high temperature ceramics (UHTCs), but their preparation is extremely difficult and costly, and they exhibit poor thermal shock resistance. Currently, boron- and silicon-containing UHTCs are mainly used for thermal protection under supersonic conditions. The principle is that during oxidation, a borosilicate glass layer forms, blocking oxygen and filling defects. However, when boron oxide is at 1200℃ and silicon dioxide at 1600℃, they rapidly evaporate, causing material degradation and ultimately failure. Although some high-melting-point oxides (such as ZrO2 and HfO2) theoretically have melting points above 2000℃, they cannot block oxygen diffusion. Therefore, to block oxygen, the thickness of these materials is usually designed to be several hundred micrometers. However, excessive material thickness often leads to undesirable cracking and poor interlayer compatibility. Therefore, it is necessary to find a high-temperature, high-efficiency oxygen diffusion barrier material to solve this problem.

[0003] Iridium (Ir) has a high melting point (2440℃), excellent corrosion resistance, and extremely low oxygen permeability at high temperatures. Even in environments with temperatures up to 2280℃, it does not chemically react with carbon. Therefore, Ir is widely used in high-temperature protective coatings, especially in applications where ambient temperatures exceed 1800℃. Furthermore, its high melting point and low oxygen permeability at temperatures between 2000 and 2200℃ make it difficult for oxygen to pass through, making it the best oxygen diffusion barrier material currently available. When the ambient temperature is above 2000℃, a 1μm thick layer of Ir exhibits superior oxidation resistance compared to a 1mm thick layer of SiO2. Therefore, Ir is highly 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 the leading edges and nose cones of hypersonic aircraft.

[0004] However, when the temperature of a pure Ir coating reaches above 1100℃, Ir is easily oxidized to form IrO3. IrO3 is prone to sublimation, ultimately leading to coating failure. Therefore, it is necessary to modify Ir by adding elements. Currently, Ir-based alloys Ir-M (M = Ti, Nb, Hf, Zr, Ta, and V) are attracting much attention as novel high-temperature materials due to their high melting point and excellent oxidation resistance. This type of coating is also known as an Ir alloy coating. Although the addition of elements has modified Ir to some extent, it has not yet achieved ideal results in preventing Ir from volatilizing after oxidation and preventing coating failure.

[0005] Therefore, developing a superior Ir alloy coating has become an urgent problem to be solved. Summary of the Invention

[0006] To address the aforementioned problems, the present invention aims to provide an Ir-Hf alloy thin film that exhibits strong oxidation resistance, effectively reduces the volatilization of Ir in the alloy film, and maintains the high-temperature performance of the alloy film.

[0007] To achieve the above objectives, the present invention provides an Ir-Hf alloy thin film, wherein the Ir-Hf alloy thin film is composed of non-equiatomic ratio or equiatomic ratio; the chemical formula of the Ir-Hf alloy in the alloy thin film is Ir-aHf, wherein a represents the atomic percentage of Hf without the percentage sign, and the value of a is 10-50.

[0008] The preparation method of this Ir-Hf alloy thin film includes the following steps:

[0009] 1) Place the substrate in anhydrous ethanol for ultrasonic cleaning for 10 minutes to remove contaminants attached to the substrate surface. After ultrasonic cleaning, rinse the substrate with deionized water.

[0010] 2) Dry the cleaned substrate with compressed nitrogen gas until its surface is clean and free of water stains;

[0011] 3) Fix the substrate with the sputtering surface facing 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 the position that completely covers the substrate.

[0012] 4) Place the Ir and Hf pure metal bulk targets on two different DC target positions in the deposition chamber, and adjust 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.

[0013] 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 × 10⁻⁶ Pa. -2 Pa;

[0014] 6) Introduce Ar gas into the deposition chamber, adjust the working gas pressure to 0.7-0.8 Pa, turn on the DC constant current power supply of the corresponding target, set the target sputtering power, and pre-sputter the target for 10-15 minutes to remove impurities on the target surface; wherein, the sputtering power of Ir target is 150 W, and the sputtering power of Hf target is 50-250 W.

[0015] 7) Set the substrate stage rotation speed to 10-30 r / min, open the substrate baffle, and perform thin film sputtering on the sputtering surface of the substrate for 30-60 min to obtain a thin film;

[0016] 8) After sputtering is completed, turn off the DC constant current power supply, turn off the Ar gas source, and turn off the substrate rotation. Allow the film to cool to room temperature under vacuum and then remove it to obtain the Ir-Hf alloy film on the substrate.

[0017] As described above, in step 1), the sputtering surface of the substrate is polished with damping cloth before ultrasonic cleaning.

[0018] As described above, the substrate in step 1) is a single-crystal Si wafer.

[0019] Preferably, the single-crystal Si wafer is P-type with a crystal orientation of [missing information]. <100> .

[0020] As described above, the ultrasonic frequency in step 1) is 60-80 Hz.

[0021] As mentioned above, the targets for Ir and Hf 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.

[0022] As described above, the angle between the target material and the center line perpendicular to the substrate stage in step 4) is 30°; the vertical distance between the pure metal block target material of Ir and Hf and the substrate stage is 10cm.

[0023] Under the same preparation parameters, the angle affects the deposition rate of the thin film. Too small or too large an angle will affect the thickness of the thin film. At 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.

[0024] As described above, in step 6), the flow rate of Ar gas is 40 sccm, and the purity is greater than or equal to 99.999%.

[0025] Regarding sputtering power, the target material is not easy to ignite when the sputtering power is lower than the required power, while when the sputtering power is higher than the required power, it is easy to cause the equipment to overheat and affect the sputtering effect.

[0026] 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 single-phase face-centered cubic solid solution structure and amorphous structure, or an amorphous structure.

[0027] 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.

[0028] The advantages of this invention are:

[0029] 1. The Ir-Hf alloy thin film provided by this invention is prepared using multi-target DC magnetron sputtering technology, i.e., co-sputtering with multiple targets, with pure metal targets as the target material. This method avoids complex target preparation processes. By changing the target power or the atomic ratio of each element in a specific target, alloy thin films with various chemical compositions can be prepared. This method features high deposition rate, wide material applicability, and good repeatability. The pure metal target material used in the preparation process of this invention is simple and readily available, making it suitable for large-scale industrial production.

[0030] 2. This invention regulates the sputtering power of Ir to 150 W to obtain a (111) oriented solid solution structure. The (111) orientation enhances oxidation resistance, while the solid solution structure improves hardness. In contrast, existing Ir structures are mostly (220) oriented, which have lower oxidation resistance than the (111) oriented structure. Even with elemental modification, the oxidation resistance of Ir cannot be improved. This invention also obtains Ir-Hf alloy films with different atomic ratios by regulating the sputtering power of Hf. When the atomic percentage of Hf is less than 30%, the film exhibits a single-phase substitution solid solution structure, significantly improving its oxidation resistance. The lowest Ir volatilization rate is 0.25 μm / h, with a maximum hardness of 19 GPa, significantly enhanced wear resistance, and a minimum surface roughness of 0.71 nm. 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, achieving a hybrid structure of solid solution and amorphous. This hybrid structure significantly improves ductility and toughness, achieving an elastic modulus of 200 GPa, and significantly enhances corrosion resistance. Furthermore, all three structures—single-phase substitution solid solution, hybrid solid solution and amorphous, and amorphous—enhance the toughness of the Ir-Hf alloy film, simultaneously achieving multiple benefits including high hardness, oxidation resistance, and corrosion resistance. The prepared Ir-Hf alloy film exhibits uniform elemental distribution and fine grains.

[0031] 3. The Ir-Hf alloy film prepared by this invention increases the volatilization temperature of pure Ir from 1100℃ by 200-300℃, and reduces the volatilization rate of Ir in the film to 0.25μm / h, which is much lower than that of pure iridium and iridium alloy coatings prepared by prior art.

[0032] 4. The Ir-Hf alloy thin film prepared by the present invention breaks through the limitations of poor orientation of thin films (220) prepared by traditional arc melting, molten salt electrodeposition, and double glow plasma deposition techniques. Moreover, the chemical composition of the prepared thin film is uniformly distributed, overcoming the disadvantage of uneven distribution of Ir-Hf modified alloy structure prepared by traditional arc melting.

[0033] 5. The Ir-Hf alloy films prepared by this invention are all about 1 μm thick, but their 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. Since Ir metal is expensive, reducing the thickness of the alloy film reduces the film quality on the one hand, and greatly reduces the production cost on the other hand.

[0034] 6. The difference in atomic radii between Ir and Hf is greater than 12%, which is more conducive to the preparation of amorphous Ir-Hf coatings, improving the overall ductility and toughness, the wear resistance of the film, and the corrosion resistance of the film.

[0035] 7. Unlike traditional Ir-Hf alloys, the Ir-Hf thin film prepared by this invention can precipitate HfO2 in situ during the oxidation process, which acts as an oxygen barrier layer to prevent oxygen from diffusing into the film, thus greatly improving the oxidation resistance of the film and greatly reducing the volatilization rate of Ir in the film.

[0036] The beneficial effects of this invention are as follows:

[0037] This invention provides an Ir-Hf alloy thin film, which is a binary alloy thin film prepared by multi-target DC magnetron sputtering technology. The structure is a single-phase face-centered cubic solid solution, a mixed structure of solid solution and amorphous structure, or an amorphous structure. The surface roughness of the alloy thin film is 0.71-2.48 nm, the hardness is 12-19 GPa, the elastic modulus is 200-380 GPa, and the oxidation rate of Ir in the film is as low as 0.25 μm / h at 1300℃, which has a wider range of application prospects. Attached Figure Description

[0038] Figure 1 This is an EDS image of the elemental composition of the Ir-10Hf alloy thin film in Example 1 of the present invention.

[0039] Figure 2 The image shows the surface morphology AFM image of the Ir-10Hf alloy thin film in Example 1 of this invention.

[0040] Figure 3 The image shows the XRD pattern of the Ir-10Hf alloy thin film in Example 1 of this invention.

[0041] Figure 4 This is an EDS image of the cross-section of the oxidized Ir-10Hf alloy thin film in Example 1 of the present invention.

[0042] Figure 5 This is an EDS image of the elemental composition of the Ir-20Hf alloy thin film in Example 2 of the present invention.

[0043] Figure 6 The image shows the surface morphology AFM image of the Ir-20Hf alloy thin film in Example 2 of this invention.

[0044] Figure 7 The image shows the XRD pattern of the Ir-20Hf alloy thin film in Example 2 of this invention.

[0045] Figure 8 This is an EDS image of the cross-section of the oxidized Ir-20Hf alloy thin film in Example 2 of the present invention.

[0046] Figure 9 This is an EDS image of the Ir-50Hf alloy thin film in Example 3 of the present invention.

[0047] Figure 10 The image shows the surface morphology AFM image of the Ir-50Hf alloy thin film in Example 3 of this invention.

[0048] Figure 11 The image shows the XRD pattern of the Ir-50Hf alloy thin film in Example 3 of this invention.

[0049] Figure 12 This is an EDS image of the cross-section of the oxidized Ir-50Hf alloy thin film in Example 3 of the present invention. Detailed Implementation

[0050] The following embodiments are provided to describe the present invention in detail and comprehensively, 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 explicit definition of the scope of protection of the present invention, but are not intended to limit the scope of the present invention.

[0051] Magnetron sputtering, with its high deposition rate, good film quality, controllable performance, and strong adhesion to the substrate, has become one of the most common methods for thin film preparation. Magnetron sputtering deposition most commonly employs single-target sputtering, where the sputtering target is a single alloy material. This technique allows for precise control of the stoichiometry of the film composition; however, its disadvantages include the complexity and high cost of alloy target preparation. With continuous advancements in fabrication technology, multi-target magnetron sputtering is increasingly being applied to the preparation of multi-principal element thin films. Multi-target magnetron sputtering uses multiple pure metal targets or binary alloy targets, effectively avoiding the complex preparation process of single alloy targets. Furthermore, by changing the target power, adjusting the sputtering sequence of different targets, and the angle of the target relative to the substrate, films with diverse compositions can be prepared, making thin film preparation more flexible and facilitating high-throughput screening of film composition and properties.

[0052] All raw materials used in the following examples are commercially available:

[0053] 1. The high-purity argon gas used in this invention was purchased from Beijing Millennium Jingcheng Gas Co., Ltd., with a purity greater than or equal to 99.999%.

[0054] 2. The Ir and Hf pure metal targets used in the thin films prepared in this invention are commercially available products with a purity greater than or equal to 99.95%, and the single-crystal Si is a commercially available product.

[0055] 3. The high-vacuum magnetron sputtering coating equipment used for the thin film prepared in this 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.

[0056] Example 1: Preparation of Ir-10Hf alloy thin film

[0057] P-type, crystal orientation <100> The pre-damped polished single-crystal Si wafer was ultrasonically cleaned with anhydrous ethanol at 60 Hz for 10 minutes to remove contaminants adhering to the substrate surface. After ultrasonic cleaning, the substrate was rinsed with deionized water and then dried with compressed nitrogen to ensure a clean, water-free surface. The single-crystal Si wafer was fixed on a substrate disk, which was then fixed on the substrate stage of the high-vacuum magnetron sputtering deposition equipment. The rotating substrate baffle was adjusted to completely cover the substrate. High-purity metal targets Ir and Hf were placed on two different DC target positions in the deposition chamber, with the angle of the target relative to the center line perpendicular to the substrate stage adjusted to 30° and the vertical distance between the target and the substrate stage adjusted to 10 cm. The deposition chamber was first evacuated to less than 5.0 Pa using a mechanical pump, and then evacuated to less than 1.0 × 10⁻⁶ Pa using a molecular pump. -2Pa; High-purity Ar gas with a purity greater than or equal to 99.999% was introduced into the deposition chamber at a flow rate of 40 sccm, and the working gas pressure was adjusted to 0.8 Pa. The power of the Ir target was set to 150 W and the power of the Hf target was set to 50 W. The targets were pre-sputtered for 10 min to remove impurities on the target surface. After the pre-sputtering was completed, the substrate rotation speed was set to 30 r / min, the substrate baffle was opened, and the formal sputtering was started for 50 min. After the sputtering was completed, the DC constant current power supply was turned off, the Ar gas source was turned off, and the substrate rotation was turned off. The film was cooled to room temperature under vacuum and then removed. The Ir-10Hf alloy film was obtained on the single crystal Si wafer.

[0058] Since the performance of the alloy thin film needs to be tested, and a single-crystal Si wafer has only one grain, the surface supporting the thin film has a single crystal orientation, which ensures that the properties are the same and stable throughout this surface. Furthermore, single-crystal Si wafers are convenient for sample preparation and cutting. Therefore, in this embodiment and subsequent embodiments, single-crystal Si wafers are chosen to support the thin film. In practical applications, different substrates can be selected to support the thin film according to requirements.

[0059] Different substrate products may be purchased with or without polishing treatment. Unpolished products require polishing to increase the adhesion between the film and the substrate. In this embodiment, because film performance needs to be tested, polishing is performed before use to prevent separation between the film and the substrate and to increase their adhesion. Subsequent embodiments will also perform polishing to ensure consistency in the experimental process.

[0060] Since a faster substrate rotation speed puts greater pressure on the equipment motor and makes it more susceptible to damage, a lower substrate rotation speed was used in this embodiment. Preliminary experiments showed that the substrate rotation speed had no substantial impact on the preparation and performance of the alloy thin film. To maintain consistency, the same substrate rotation speed was used in subsequent embodiments.

[0061] Experiments showed that sputtering time had no effect on the alloy composition, but it did affect the film thickness. In this embodiment, sputtering for 50 minutes yielded a film with a thickness of approximately 1 μm, suitable for subsequent performance testing of samples. The same sputtering time was used in later embodiments to facilitate performance testing of the samples. In practical applications, different sputtering times can be selected according to different film thicknesses.

[0062] The chemical composition of the multi-principal alloy thin film was analyzed using an Oxford X-act energy dispersive spectroscopy (EDS, mounted on a scanning electron microscope). The elemental surface scanning EDS spectra of the multi-principal alloy thin film are shown below. Figure 1 As shown; where, Figure 1a) shows the surface morphology of the sample; b) shows the distribution spectrum of Ir in the sample; and c) shows the distribution spectrum of Hf in the sample. According to the quantitative calculation results of the software, the composition of the alloy film is Ir-10Hf.

[0063] The surface morphology of the Ir-10Hf alloy thin film was imaged using a Dimension ICON atomic force microscope (AFM) from Bruker GmbH, Germany, in tapping mode. The scanning area was 2 μm × 2 μm. The surface roughness (Ra) of the film was analyzed using NanoScope Analysis software. The results are as follows: Figure 2 As shown, the surface AFM morphology of the Ir-10Hf multi-principal-element alloy thin film is needle-like, and the surface roughness is 0.71 nm.

[0064] The surface roughness of a thin film affects its wear resistance. A surface with Ra < 1 nm is considered ultra-smooth, while a surface with Ra < 10 nm is considered smooth. The coefficient of friction and wear rate of a thin film generally increase with increasing surface roughness. This is because a rough surface has a smaller contact area and higher contact pressure, leading to a higher coefficient of friction and wear loss. Therefore, a smaller surface roughness is beneficial for improving the wear resistance of the thin film.

[0065] XRD phase analysis of Ir-10Hf alloy thin films was performed using a D8 Advance X-ray diffractometer (XRD) from BRUKER AXS GmbH, Germany. The operating voltage was 40 kV, the operating current was 40 mA, the X-ray source was Cu-Ka (λ = 0.15418 nm), the grazing incidence angle was 1°, the scanning speed was 4° / min, the scanning step size was 0.02° / step, and the scanning range was 10°–90°. The results are as follows: Figure 3 As shown: Based on the extinction law of lattice diffraction, 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, respectively, indicating that the crystal structure of the Ir-10Hf alloy film is a face-centered cubic (FCC) solid solution structure.

[0066] Since thin films are micro- and nano-scale materials, their hardness can only be measured using a nanoindenter. Vickers hardness and Rockwell hardness, which are typically used to measure the hardness of bulk alloys, cannot be used to measure the hardness of thin films. Therefore, an Agilent Technologies Nano Indenter G200 nanoindenter was used in continuous stiffness mode to test the hardness of Ir-10Hf alloy thin films. The results showed that the nanoindentation hardness of the Ir-10Hf alloy thin film reached as high as 19 GPa, making it suitable for applications in high-hardness and wear-resistant fields.

[0067] Isothermal oxidation experiments were conducted on the alloy thin film. The alloy thin film was placed in a muffle furnace at 1300℃ and oxidized for 15 min. After cooling, it was scanned by EDS to calculate the oxidation and volatilization rate of Ir in the film. Figure 4 As shown; where, Figure 4 In Figure a), the cross-sectional morphology of the sample after oxidation corresponds to the original sample thickness; in figure b), the distribution spectrum of Ir element in the oxidized sample is shown. The volatilization rate of Ir element is obtained by calculating the volatilization thickness. Figure 4 It can be seen that the volatilization rate of Ir element was calculated to be 0.25 μm / h after obtaining the distribution of Ir element by EDS scanning analysis after 15 min of oxidation.

[0068] Example 2: Preparation of Ir-20Hf alloy thin film

[0069] P-type, crystal orientation <100> The pre-damped polished single-crystal Si wafer was ultrasonically cleaned with anhydrous ethanol at 60 Hz for 10 minutes to remove contaminants adhering to the substrate surface. After ultrasonic cleaning, the substrate was rinsed with deionized water and then dried with compressed nitrogen to ensure a clean, water-free surface. The single-crystal Si wafer was fixed on a substrate disk, which was then fixed on the substrate stage of the high-vacuum magnetron sputtering deposition equipment. The rotating substrate baffle was adjusted to completely cover the substrate. High-purity metal targets Ir and Hf were placed on two different DC target positions in the deposition chamber, with the angle of the target relative to the center line perpendicular to the substrate stage adjusted to 30° and the vertical distance between the target and the substrate stage adjusted to 10 cm. The deposition chamber was first evacuated to less than 5.0 Pa using a mechanical pump, and then evacuated to less than 1.0 × 10⁻⁶ Pa using a molecular pump. -2 Pa; High-purity Ar gas with a purity greater than or equal to 99.999% was introduced into the deposition chamber at a flow rate of 40 sccm, and the working gas pressure was adjusted to 0.8 Pa. The power of the Ir target was set to 150 W and the power of the Hf target was set to 85 W. The targets were pre-sputtered for 10 min to remove impurities on the target surface. After the pre-sputtering was completed, the substrate rotation speed was set to 30 r / min, the substrate baffle was opened, and the formal sputtering was started for 45 min. After the sputtering was completed, the DC constant current power supply was turned off, the Ar gas source was turned off, and the substrate rotation was turned off. The film was cooled to room temperature under vacuum and then removed. The Ir-20Hf alloy film was obtained on the single crystal Si wafer.

[0070] The chemical composition of the multi-principal alloy thin film was analyzed using an Oxford X-act energy dispersive spectroscopy (EDS, mounted on a scanning electron microscope). The elemental surface scanning EDS spectra of the multi-principal alloy thin film are shown below. Figure 5 As shown; where, Figure 5a) shows the surface morphology of the sample; b) shows the distribution spectrum of Ir element in the sample; and c) shows the distribution spectrum of Hf element in the sample. According to the quantitative calculation results of the software, the composition of the alloy film is Ir-20Hf.

[0071] The surface morphology of the Ir-20Hf alloy thin film was imaged using a Dimension ICON atomic force microscope (AFM) from Bruker GmbH, Germany, in tapping mode. The scanning area was 2 μm × 2 μm. The surface roughness (Ra) of the film was analyzed using NanoScope Analysis software. The results are as follows: Figure 6 As shown, the surface AFM morphology of the Ir-20Hf multi-principal-element alloy thin film is needle-like, and the surface roughness is 1.03 nm.

[0072] XRD phase analysis of Ir-10Hf alloy thin films was performed using a D8 Advance X-ray diffractometer (XRD) from BRUKER AXS GmbH, Germany. The operating voltage was 40 kV, the operating current was 40 mA, the X-ray source was Cu-Ka (λ = 0.15418 nm), the grazing incidence angle was 1°, the scanning speed was 4° / min, the scanning step size was 0.02° / step, and the scanning range was 10°–90°. The results are as follows: Figure 7 As shown: Based on the extinction rules of lattice diffraction, 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, respectively, indicating that the crystal structure of the Ir-20Hf alloy film is a face-centered cubic (FCC) solid solution structure.

[0073] The hardness of the Ir-20Hf alloy film was tested using a Nano Indenter G200 nanoindenter manufactured by Agilent Technologies in continuous stiffness mode. The results showed that the nanoindentation hardness of the Ir-20Hf alloy film was 13 GPa, which can be used in high-hardness and wear-resistant fields.

[0074] Isothermal oxidation experiments were conducted on the alloy thin film. The alloy thin film was placed in a muffle furnace at 1300℃ and oxidized for 15 min. After cooling, it was scanned by EDS to calculate the oxidation and volatilization rate of Ir in the film. Figure 8 As shown, where, Figure 8 In Figure a), the cross-sectional morphology of the sample after oxidation corresponds to the original sample thickness; in figure b), the distribution spectrum of Ir element in the oxidized sample is shown. The volatilization rate of Ir element is obtained by calculating the volatilization thickness. Figure 8 It can be seen that the volatilization rate of Ir element was calculated to be 0.85 μm / h after obtaining the distribution of Ir element by EDS scanning analysis after 15 min of oxidation.

[0075] Example 3: Preparation of Ir-50Hf alloy thin film

[0076] P-type, crystal orientation <100> The pre-damped polished single-crystal Si wafer was ultrasonically cleaned with anhydrous ethanol at 60 Hz for 10 minutes to remove contaminants adhering to the substrate surface. After ultrasonic cleaning, the substrate was rinsed with deionized water and then dried with compressed nitrogen to ensure a clean, water-free surface. The single-crystal Si wafer was fixed on a substrate disk, which was then fixed on the substrate stage of the high-vacuum magnetron sputtering deposition equipment. The rotating substrate baffle was adjusted to completely cover the substrate. High-purity metal targets Ir and Hf were placed on two different DC target positions in the deposition chamber, with the angle of the target relative to the center line perpendicular to the substrate stage adjusted to 30° and the vertical distance between the target and the substrate stage adjusted to 10 cm. The deposition chamber was first evacuated to less than 5.0 Pa using a mechanical pump, and then evacuated to less than 1.0 × 10⁻⁶ Pa using a molecular pump. -2 Pa; High-purity Ar gas with a purity greater than or equal to 99.999% was introduced into the deposition chamber at a flow rate of 40 sccm, and the working gas pressure was adjusted to 0.8 Pa. The power of the Ir target was set to 150 W and the power of the Hf target was set to 250 W. The targets were pre-sputtered for 10 min to remove impurities on the target surface. After the pre-sputtering was completed, the substrate rotation speed was set to 30 r / min, the substrate baffle was opened, and the formal sputtering was started for 30 min. After the sputtering was completed, the DC constant current power supply was turned off, the Ar gas source was turned off, and the substrate rotation was turned off. The film was cooled to room temperature under vacuum and then removed. The Ir-50Hf alloy film was obtained on the single crystal Si wafer.

[0077] The chemical composition of the multi-principal alloy thin film was analyzed using an Oxford X-act energy dispersive spectroscopy (EDS, mounted on a scanning electron microscope). The elemental surface scanning EDS spectra of the multi-principal alloy thin film are shown below. Figure 9 As shown; where, Figure 9 a) shows the surface morphology of the sample; b) shows the distribution spectrum of Ir in the sample; and c) shows the distribution spectrum of Hf in the sample. According to the quantitative calculation results of the software, the composition of the alloy film is Ir-50Hf.

[0078] The surface morphology of the Ir-50Hf alloy thin film was imaged using a Dimension ICON atomic force microscope (AFM) from Bruker GmbH, Germany, in tapping mode. The scanning area was 2 μm × 2 μm. The surface roughness (Ra) of the film was analyzed using NanoScope Analysis software. The results are as follows: Figure 10 As shown, the surface AFM morphology of the Ir-50Hf multi-principal-element alloy thin film is needle-like, and the surface roughness is 0.79 nm.

[0079] XRD phase analysis of Ir-50Hf alloy thin films was performed using a D8 Advance X-ray diffractometer (XRD) from BRUKER AXS GmbH, Germany. The operating voltage was 40 kV, the operating current was 40 mA, the X-ray source was Cu-Ka (λ = 0.15418 nm), the grazing incidence angle was 1°, the scanning speed was 4° / min, the scanning step size was 0.02° / step, and the scanning range was 10°–90°. The results are as follows: Figure 11 As shown, it can be determined that the Ir-50Hf alloy thin film has an amorphous structure.

[0080] The hardness of Ir-50Hf alloy films was tested using a Nano Indenter G200 nanoindenter manufactured by Agilent Technologies in continuous stiffness mode. The results showed that the nanoindentation hardness of the Ir-50Hf alloy films reached 14 GPa, which can be used in high-hardness and wear-resistant fields.

[0081] Isothermal oxidation experiments were conducted on the alloy thin film. The alloy thin film was placed in a muffle furnace at 1300℃ and oxidized for 15 min. After cooling, it was scanned by EDS to calculate the oxidation and volatilization rate of Ir in the film. Figure 12 As shown, where, Figure 12 In Figure a), the cross-sectional morphology of the sample after oxidation corresponds to the original sample thickness; in figure b), the distribution spectrum of Ir element in the oxidized sample is shown. The volatilization rate of Ir element is obtained by calculating the volatilization thickness. Figure 12 It can be seen that the volatilization rate of Ir element was calculated to be 2.65 μm / h after obtaining the distribution of Ir element by EDS scanning analysis after 15 min of oxidation.

[0082] As can be seen from the above embodiments, the present invention provides an Ir-Hf alloy thin film, which is fabricated using multi-target DC magnetron sputtering technology. The resulting film has a hardness of 12 GPa to 19 GPa and a surface roughness reaching mirror level, effectively enhancing the wear resistance of the film. The in-situ precipitation of HfO2 promotes an extremely low Ir volatilization rate in the film, as low as 0.25 μm / h, greatly improving its oxidation resistance. With the increase of Hf content, the film transforms from a single-phase face-centered cubic solid solution to an amorphous structure, improving the corrosion resistance of the film.

[0083] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. An Ir-Hf alloy thin film, characterized in that, The Ir-Hf alloy film is composed of non-equivalent atomic ratios or equivalent atomic ratios; the chemical formula of the Ir-Hf alloy in the alloy film is Ir-aHf, where a represents the atomic percentage of Hf without the percentage sign, and the value of a is 10-50. The preparation method of this Ir-Hf alloy thin film includes the following steps: 1) Place the substrate in anhydrous ethanol for ultrasonic cleaning for 10 minutes to remove contaminants attached to the substrate surface. After ultrasonic cleaning, rinse the substrate with deionized water. 2) Dry the cleaned substrate with compressed nitrogen gas until its surface is clean and free of water stains; 3) Fix the substrate with the sputtering surface facing 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 the position that completely covers the substrate. 4) Place the Ir and Hf pure metal bulk targets on two different DC target positions in the deposition chamber, and adjust 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 × 10⁻⁶ Pa. -2 Pa; 6) Introduce Ar gas into the deposition chamber, adjust the working gas pressure to 0.7~0.8 Pa, turn on the DC constant current power supply of the corresponding target, set the target sputtering power, and pre-sputter the target for 10~15 min to remove impurities on the target surface; wherein, the sputtering power of Ir target is 150 W, and the sputtering power of Hf target is 50~250 W. 7) Set the substrate stage rotation speed to 10~30 r / min, open the substrate baffle, and perform thin film sputtering on the sputtering surface of the substrate for 30~60 min to obtain the thin film; 8) After sputtering is completed, turn off the DC constant current power supply, turn off the Ar gas source, and turn off the substrate rotation. Allow the film to cool to room temperature under vacuum and then remove it to obtain the Ir-Hf alloy film on the substrate. Among them, 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℃ is 0.25~2.65 μm / h.

2. The Ir-Hf alloy thin film according to claim 1, characterized in that, Further steps include: Step 1) Polishing the sputtering surface of the substrate with damping cloth before ultrasonic cleaning.

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

4. The Ir-Hf alloy thin film according to claim 3, characterized in that, The single-crystal Si wafer is P-type with a crystal orientation of [missing information]. <100> .

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

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

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

8. The Ir-Hf alloy thin film according to claim 1, characterized in that, In step 6), the flow rate of Ar gas is 40 sccm, and the purity is greater than or equal to 99.999%.

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

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