A quaternary alloy doped diamond-like thin film and a method for preparing the same

Abstract

The application discloses a quaternary alloy doped diamond-like film and a preparation method thereof, and belongs to the technical field of high-entropy carbide films. The film is obtained by high-power pulse magnetron sputtering of a HfMoNbZr quaternary alloy target and direct-current magnetron sputtering of a carbon target with a silicon wafer as a substrate. The atomic percentage content of each element in the film is as follows: Hf 3.55-9.46%, Mo 3.70-12.08%, Nb 3.19-11.63%, Zr 3.12-11.66% and C 55.17-86.44%. The film has a face-centered cubic structure (FCC), and the fracture morphology shows a dense structure. The application has low trial and error cost, simple process, and can be used for mass production. The film can effectively improve the hardness of the film, and the prepared film is suitable for a mold surface protective layer and can prolong the service life of a workpiece.

Description

Technical Field

[0001] This invention belongs to the field of diamond thin film technology, and relates to a quaternary alloy doped diamond thin film, as well as a method for preparing the quaternary alloy doped diamond thin film and its applications. Background Technology

[0002] Diamond-like carbon (DLC) films are films containing a certain amount of diamond bonds (sp). 2 and sp 3 Metastable films of amorphous carbon have the characteristics of high hardness, low coefficient of friction, good wear resistance and high chemical inertness. However, DLC films have defects such as low adhesion and high residual stress, which limit the application of DLC films. Studies have shown that adding metals to DLC films can release internal stress, stabilize the film structure, and thus enhance adhesion, wear resistance, toughness and thermal stability. Chinese patent application (publication number CN203546141U) dops several layers of nanoscale metal-containing diamond-like carbon (e.g., tungsten-containing diamond-like carbon DLC-W) structures into a pure DLC film, effectively alleviating the internal stress of the diamond-like carbon film itself and also effectively increasing the adhesion between the film and the substrate, allowing the film thickness to exceed 10 μm and exhibiting scratch adhesion strength exceeding 100 N. In addition, Chinese patent application (publication number CN102817008B) uses DC magnetron and RF magnetron co-sputtering methods to prepare Ag and Ti co-doped DLC films, achieving a maximum adhesion strength of 16 N and a maximum hardness of 1286 Hv. However, the above-mentioned preparation processes did not significantly improve the film hardness after the addition of metal.

[0003] In recent years, the research, development, preparation, and application of diamond-like carbon (DLC) films have been advancing in both depth and breadth, leading to the development of numerous preparation methods. However, the composition, structure, and performance of DLC films vary significantly depending on the preparation method. The aforementioned Chinese patent application (publication number CN102817008B) utilizes DC magnetron and RF magnetron co-sputtering methods to obtain a DLC film with low internal stress, good thermal stability, and antibacterial properties, but significant room for improvement in hardness remains. The advantage of existing high-power pulsed magnetron sputtering (HiPIMS) technology lies in its higher ionization rate compared to traditional magnetron sputtering, thus offering advantages in obtaining coatings with higher density and hardness. Summary of the Invention

[0004] The technical problem this invention aims to solve is to provide a quaternary alloy-doped diamond-like carbon (DLC) thin film and its preparation method. This method utilizes both high-power pulsed magnetron sputtering and DC magnetron sputtering techniques to prepare a quaternary alloy-doped DLC thin film, thus offering advantages in obtaining coatings with higher density and hardness. This provides a theoretical basis and application value for the future development of DLC thin film materials, addressing the problems in existing technologies.

[0005] The technical solution adopted in this invention is as follows: a quaternary alloy-doped diamond-like thin film, which is obtained by co-deposition of a silicon wafer as a substrate by high-power pulsed magnetron sputtering of an HfMoNbZr quaternary alloy target and DC magnetron sputtering of a carbon target. The atomic percentage content of each element in the film is Hf 3.55~9.46%, Mo 3.70~12.08%, Nb 3.19~11.63%, Zr 3.12~11.66%, and C 55.17~86.44%.

[0006] Furthermore, the aforementioned film has a face-centered cubic (FCC) structure and exhibits a dense fracture morphology.

[0007] Furthermore, the hardness of the above-mentioned film is 9.4~21.6 GPa, and the elastic modulus is 97.9~194.5 GPa.

[0008] Furthermore, the purity of the HfMoNbZr quaternary alloy target is >99.99%, the purity of the carbon target is >99.98%, and the atomic ratio in the HfMoNbZr quaternary alloy target is 1:1:1:1.

[0009] Furthermore, the silicon wafers of the aforementioned substrate are polished on one side and have a thickness of 489~510μm.

[0010] Furthermore, the power supplies used in the aforementioned high-power pulsed magnetron sputtering and DC magnetron sputtering are a high-power pulsed magnetron power supply and a DC power supply, respectively.

[0011] A method for preparing a quaternary alloy-doped diamond-like thin film includes the following steps:

[0012] Step 1: Before mounting the silicon wafer substrate, rinse it with deionized water, then clean it with petroleum ether solution and anhydrous ethanol in an ultrasonic bath at a frequency of 30kHz for 15-30 minutes, and then dry its surface with a hair dryer.

[0013] Step 2, Thin Film Deposition: Under vacuum conditions, using HfMoNbZr quaternary alloy target and carbon target as target materials and silicon wafer as substrate, inert argon gas is introduced for thin film deposition. The thin film is obtained by co-deposition of HfMoNbZr quaternary alloy target by high-power pulsed magnetron sputtering and carbon target by DC magnetron sputtering with silicon wafer as substrate.

[0014] Furthermore, in step one above, the specific operation for removing oil and adhesive is as follows: first, rinse with deionized water, then place the silicon wafer in petroleum ether solution and anhydrous ethanol reagent and clean it in ultrasonic at a frequency of 30kHz for 15~30 minutes respectively. After cleaning, use a hair dryer to dry its surface.

[0015] Furthermore, in step two above, the conditions for thin film deposition are as follows: the distance between the quaternary alloy target and the carbon target and the silicon substrate is 8~11 cm, and the background vacuum is less than 2×10⁻⁶. -3 Pa, heating temperature ≥500℃, deposition time 180min, using a high-power pulsed power supply to sputter a quaternary alloy target with a power of 100-300W, using a DC power supply to sputter a carbon target with a power of 245-255W, argon flow rate 38~42sccm, argon purity ≥99.99%.

[0016] Application of a quaternary alloy-doped diamond-like thin film in the preparation of a protective layer for mold surfaces.

[0017] The beneficial effects of this invention are as follows: Compared with the prior art, this invention uses high-power pulsed magnetron sputtering and DC magnetron sputtering technologies to jointly prepare a quaternary alloy-doped diamond-like carbon (DLC) film, reducing the trial-and-error cost of film preparation, making it easier to precisely control the element content in the film, simplifying the process, and exhibiting excellent mechanical properties. This provides an advantage in improving the service life of molds and expands the database of alloy-doped DLC films, providing ideas for the future preparation of alloy-doped DLC films. Furthermore, the elements used in this film are all refractory metals, and it contains three strong carbon compound elements (Hf, Nb, Zr) and one weak carbon compound element (Mo), which can reduce I... D / I G This greatly improves the sp content in the thin film. 3The content increases the film hardness. In preparing quaternary alloy-doped diamond-like carbon films, this invention previously attempted to use DC magnetron sputtering technology, but this did not significantly improve the film hardness, and a porous structure appeared in the film, reducing the film quality. However, the film obtained by co-deposition using high-power pulsed magnetron sputtering technology with DC magnetron sputtering showed a significant improvement in film hardness and was much denser. Based on this, the inventors adjusted their research and development approach, breaking free from the barriers of existing technologies. They modified the preparation method, using a quaternary alloy target of HfMoNbZr to be deposited by high-power pulsed magnetron sputtering and a carbon target to be deposited by DC magnetron sputtering to obtain a thin film. The dense structure of this method is mainly due to the higher energy of the sputtered material in high-power pulsed magnetron sputtering compared to DC magnetron sputtering. Furthermore, in high-power pulsed magnetron sputtering, the irradiation of metal ions during the film growth process eliminates voids within the columns, resulting in a nearly completely dense layer and a co-columnar NaCl-like FCC structure with an average column diameter. In short, high-power pulsed magnetron sputtering uses high-power pulses to generate dense plasma, with a plasma density 2-4 orders of magnitude higher than that of DC magnetron sputtering. This allows high-power pulsed magnetron sputtering to prepare smoother and denser coatings. Typically, adding Mo during thin film preparation produces MoC, which significantly reduces hardness. However, in this invention, the inventors discovered that because the binding energies of Nb, Hf, and Zr with C are stronger than those of Mo with C, and because Mo has the smallest atomic radius compared to other metals, it cannot replace the metals in other carbides. Therefore, I D / I G continuously decreasing, sp 3 The hardness increases continuously and significantly, while Hf and Mo elements have a significant synergistic strengthening effect, giving the film a toughening effect. Furthermore, the atomic ratio of the elements in this invention has a crucial influence on the performance and structure of the diamond-like carbon film; only within the conditions of this invention can a trend of continuously increasing hardness occur. Attached Figure Description

[0018] Figure 1 The XRD patterns of the quaternary alloy-doped diamond-like thin films prepared in Examples 1-3 of this invention are shown.

[0019] Figure 2 This is a cross-sectional morphology diagram of the quaternary alloy doped with diamond-like carbon prepared in Example 3 of the present invention.

[0020] Figure 3 The hardness of the quaternary alloy-doped diamond-like thin film prepared in Examples 1-3 of this invention is given.

[0021] Figure 4 Raman fitting I for the quaternary alloy-doped diamond-like thin films prepared in Examples 1-3 of this invention D / I GVariation chart. Detailed Implementation

[0022] The present invention will be further described below with reference to specific embodiments.

[0023] A method for preparing a quaternary alloy-doped diamond-like thin film includes the following steps:

[0024] Step 1: Using HfMoNbZr quaternary alloy targets and carbon targets as raw materials, with approximately equal atomic ratios in the HfMoNbZr quaternary alloy targets, remove oil and adhesive from the surface of the silicon wafer substrate: After rinsing the silicon wafer with deionized water, use petroleum ether and anhydrous ethanol in sequence (petroleum ether is mainly used to clean oil and adhesive on the silicon wafer, but if petroleum ether remains on the silicon wafer, it will affect the subsequent coating, so alcohol is used to clean the fine dust and residual petroleum ether on the silicon wafer after this step) for 30 minutes each in ultrasonic cleaning at a frequency of 30kHz. After cleaning, use a hair dryer to dry it. During the drying process, keep the silicon wafer substrate and the hair dryer outlet in a straight line and at a 45° angle to the ground (a certain angle ensures that the anhydrous ethanol flows in a low-angle direction during drying, preventing droplets from remaining on the silicon wafer);

[0025] Step 2: Fix the dried silicon wafer substrate onto the sample stage, place it on the rotating stage, close the substrate baffle, and fix the quaternary alloy target and carbon target onto the copper platform connected to the high-power pulsed magnetron power supply and DC power supply, respectively. Magnets with unbalanced magnetic fields are mounted on the back of the copper platform. The target spacing is 9 cm. Close the chamber door and evacuate to a background vacuum of 2 × 10⁻⁶. -3 Pa, heat the substrate to 500℃ and hold for 30 min, introduce inert argon gas to control the film deposition pressure; turn on the high-power pulse power supply to sputter the quaternary alloy target at a power of 100-300W, turn on the DC power supply to sputter the carbon target at a power of 245-255W, pre-sputter for 10 min to remove impurities on the target surface, after 10 min, turn on the substrate baffle to deposit the quaternary alloy doped diamond-like carbon film, the sample rotation speed is 15 r / min, the deposition time is 180 min, after the film is deposited, turn off the cathode power supply, cool to 80℃ and then take out the sample.

[0026] Examples 1-3 were prepared following the steps outlined above for the preparation of quaternary alloy-doped diamond-like carbon (DLC) films, with slight differences in details. The films prepared in each example were subjected to tests for microstructure cross-sectional morphology, hardness, and abrasion resistance. The specific testing methods are as follows:

[0027] This invention utilizes a high-vacuum magnetron sputtering deposition machine to prepare thin films. The cross-sectional morphology of the prepared thin films was obtained by scanning electron microscopy (Sigma 300); the phase structure of the thin films was obtained by X-ray diffraction (XPert PRO MPD); the microstructure of the thin films was obtained by micro-laser Raman spectroscopy (WITec alpha300R); and the nanohardness of the thin films was measured by nanoindentation (TTX-NHT3).

[0028] Example 1: Specific process parameters for preparing quaternary alloy-doped diamond-like carbon thin films using high-power pulsed magnetron sputtering in this example: background vacuum level is 2×10⁻⁶. -3 Pa, the target material is fixed at 45° to the horizontal direction, the target spacing is 11cm, the substrate deposition temperature is greater than 500℃, the argon flow rate during film deposition is 38sccm, the film deposition pressure is 0.48Pa, the high-power pulsed power supply sputters the quaternary alloy target with a power of 100W, the DC power supply sputters the carbon target with a power of 245W, the deposition time is 180min, and the sample is taken out after cooling to 80℃.

[0029] The results of this embodiment show that the calculated atomic percentages of each element in the thin film are Hf 3.55%, Mo 3.70%, Nb 3.19%, Zr 3.12%, and C 86.44%; the phase structure is as follows. Figure 1 As shown, it exhibits an amorphous structure; its hardness was measured to be 9.4 GPa. Figure 3 ); I D / I G =1.0184 ( Figure 4 ).

[0030] Example 2: Specific process parameters for preparing quaternary alloy-doped diamond-like carbon thin films using high-power pulsed magnetron sputtering in this example: background vacuum level is 2×10⁻⁶. -3 Pa, the target material is fixed at 45° to the horizontal direction, the target spacing is 10cm, the substrate deposition temperature is greater than 500℃, the argon flow rate during film deposition is 39sccm, the film deposition gas pressure is 0.50Pa, the high-power pulsed power supply sputters the quaternary alloy target with a power of 200W, the DC power supply sputters the carbon target with a power of 250W, the deposition time is 180min, and the sample is taken out after cooling to 85℃.

[0031] The results of this embodiment show that the calculated atomic percentages of each element in the thin film are Hf 6.69%, Mo 8.53%, Nb 7.59%, Zr 8.10%, and C 69.09%; it has a single-phase face-centered cubic solid solution (FCC) structure; and a hardness of 12.8 GPa. Figure 3 ); I D / I G =1.0097 ( Figure 4 ).

[0032] Example 3: Specific process parameters for preparing quaternary alloy-doped diamond-like carbon thin films using high-power pulsed magnetron sputtering in this example: background vacuum level is 2×10⁻⁶. -3 Pa, the target material is fixed at 45° to the horizontal direction, the target spacing is 10cm, the substrate deposition temperature is greater than 500℃, the argon flow rate during film deposition is 40sccm, the film deposition pressure is 0.45Pa, the high-power pulsed power supply sputters the quaternary alloy target with a power of 300W, the DC power supply sputters the carbon target with a power of 255W, the deposition time is 180min, and the sample is taken out after cooling to 88℃.

[0033] The results of this embodiment show that the calculated atomic percentages of each element in the thin film are Hf 9.46%, Mo 12.08%, Nb 11.63%, Zr 11.66%, and C 55.17%; it has a single-phase face-centered cubic solid solution (FCC) structure; and a hardness of 21.6 GPa. Figure 3 ); I D / I G =1.0007 ( Figure 4 ).

[0034] Comparative Example 1: The specific process parameters for preparing quaternary alloy-doped diamond-like carbon thin films using DC magnetron sputtering in this comparative example are as follows: background vacuum level is 2 × 10⁻⁶. -3 The target was fixed at a 45° angle to the horizontal, with a target spacing of 11 cm. The substrate deposition temperature was greater than 500℃. The argon flow rate during film deposition was 40 sccm, and the film deposition pressure was 0.47 Pa. A DC power supply was used to sputter a quaternary alloy target and a carbon target, with a power of 70 W for the quaternary alloy target and 250 W for the carbon target. The deposition time was 180 min, and the sample was removed after cooling to 83℃.

[0035] The results of this comparative example show that the calculated atomic percentages of each element in the thin film are Hf 13.77%, Mo 14.63%, Nb 13.96%, Zr 13.50%, and C 44.14%; face-centered cubic (FCC) structure and hexagonal close-packed structure (Hex.); and a hardness of 16.3 GPa.

[0036] Comparative Example 2: Specific process parameters for preparing quaternary alloy-doped diamond-like carbon thin films using only DC magnetron sputtering in this comparative example: background vacuum level of 2 × 10⁻⁶. -3 Pa, the target material is fixed at 45° to the horizontal direction, the target spacing is 11cm, the substrate deposition temperature is greater than 500℃, the argon flow rate during film deposition is 38sccm, the film deposition gas pressure is 0.47Pa, the DC power supply sputters quaternary alloy target and carbon target, the power of quaternary alloy target is 90W, the power of carbon target is 250W, the deposition time is 180min, and the sample is taken out after cooling to 82℃.

[0037] The results of this embodiment show that the calculated atomic percentages of each element in the thin film are Hf 14.39%, Mo 15.03%, Nb 13.76%, Zr 13.99%, and C 42.83%; the structure is face-centered cubic (FCC) and hexagonal close-packed (Hex.); the hardness is 16.5 GPa, and the hardness has not been significantly improved.

[0038] Comparative Example 3: Specific process parameters for preparing quaternary alloy-doped diamond-like carbon thin films using only DC magnetron sputtering in this comparative example: background vacuum level of 2 × 10⁻⁶. -3 Pa, the target material is fixed at 45° to the horizontal direction, the target spacing is 11 cm, the substrate deposition temperature is greater than 500℃, the argon flow rate during film deposition is 38 sccm, the film deposition gas pressure is 0.47 Pa, the DC power supply sputters quaternary alloy target and carbon target, the power of quaternary alloy target is 110 W, the power of carbon target is 250 W, the deposition time is 180 min, and the sample is taken out after cooling to 82℃.

[0039] The results of this embodiment show that the calculated atomic percentages of each element in the thin film are Hf 14.59%, Mo 15.50%, Nb 14.44%, Zr 14.55%, and C 40.92%; face-centered cubic (FCC) structure and hexagonal close-packed structure (Hex.); the hardness is 17.2 GPa, and the hardness has not been significantly improved.

[0040] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of protection of the claims.

Claims

1. A quaternary alloy-doped diamond-like thin film, characterized in that: The thin film was obtained by co-deposition of a silicon wafer as a substrate using a quaternary alloy target of HfMoNbZr via high-power pulsed magnetron sputtering and a carbon target via DC magnetron sputtering. The atomic percentage contents of each element in the thin film are Hf 3.55~9.46%, Mo 3.70~12.08%, Nb 3.19~11.63%, Zr 3.12~11.66%, and C 55.17~86.44%. The thin film has a face-centered cubic (FCC) structure and exhibits a dense fracture morphology.

2. The quaternary alloy-doped diamond-like thin film according to claim 1, characterized in that: The film has a hardness of 9.4~21.6 GPa and an elastic modulus of 97.9~194.5 GPa.

3. The quaternary alloy-doped diamond-like thin film according to claim 1, characterized in that: The purity of the HfMoNbZr quaternary alloy target is >99.99%, the purity of the carbon target is >99.98%, and the atomic ratio in the HfMoNbZr quaternary alloy target is 1:1:1:

1.

4. The quaternary alloy-doped diamond-like thin film according to claim 3, characterized in that: The silicon wafer used as the substrate is polished on one side and has a thickness of 489~510μm.

5. The quaternary alloy-doped diamond-like thin film according to claim 1, characterized in that: The power supplies used for the high-power pulsed magnetron sputtering and DC magnetron sputtering are a high-power pulsed magnetron power supply and a DC power supply, respectively.

6. A method for preparing a quaternary alloy-doped diamond-like thin film as described in claim 1, characterized in that, Includes the following steps: Step 1: Before mounting the silicon wafer substrate, rinse it with deionized water, then clean it with petroleum ether solution and anhydrous ethanol in an ultrasonic bath at a frequency of 30kHz for 15-30 minutes, and then dry its surface with a hair dryer. Step 2, Thin Film Deposition: Under vacuum conditions, using HfMoNbZr quaternary alloy target and carbon target as target materials and silicon wafer as substrate, thin film deposition is carried out in a high-vacuum magnetron sputtering coating machine by introducing inert gas argon. The thin film is obtained by co-deposition of HfMoNbZr quaternary alloy target by high-power pulsed magnetron sputtering and carbon target by DC magnetron sputtering with silicon wafer as substrate.

7. The method for preparing a quaternary alloy-doped diamond-like thin film according to claim 6, characterized in that: In step two, the conditions for thin film deposition are as follows: the distance between the quaternary alloy target and the carbon target and the silicon substrate is 8-11 cm, and the background vacuum is less than 2 × 10⁻⁶. -3 Pa, heating temperature ≥500℃, deposition time 180min, using a high-power pulsed power supply to sputter a quaternary alloy target with a power of 100-300W, using a DC power supply to sputter a carbon target with a power of 245-255W, argon flow rate 38~42sccm, argon purity ≥99.99%.

8. The application of the quaternary alloy-doped diamond-like thin film prepared by the method of preparing a quaternary alloy-doped diamond-like thin film according to claim 6 or 7 in the preparation of a protective layer on the surface of a mold.

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