Apparatus and method for preparing diamond-like carbon films by magnetron sputtering combined with PECVD

Abstract

This invention relates to the field of surface engineering technology, and in particular to an apparatus and method for preparing diamond-like carbon (DLC) films using magnetron sputtering combined with PECVD. The invention provides an apparatus and method for preparing DLC ​​films. It employs a PECVD apparatus with a double-layer grid, firstly using magnetron sputtering to prepare a metal transition layer, achieving a smooth transition from the substrate to the DLC coating. Combined with the double-layer grid structure, a dense DLC film layer is obtained, thereby achieving the preparation of a DLC film layer with both good corrosion resistance and abrasion resistance.

Description

Technical Field

[0001] This invention relates to the field of surface engineering technology, and in particular to an apparatus and method for preparing diamond-like films by magnetron sputtering composite PECVD. Background Technology

[0002] Diamond-like carbon (DLC) coatings are primarily composed of carbon, consisting of graphite and diamond phases. They are widely used in machinery manufacturing, automotive engines, and aerospace due to their excellent lubrication properties (friction coefficient can be below 0.2) and corrosion resistance. However, due to ion bombardment, particle deposition, and growth defects during the DLC coating deposition process, DLC films may contain defects such as pinholes, cracks, and weak interfacial bonding points. In corrosive environments, corrosive solutions can penetrate the substrate or the transition layer between the DLC film and the substrate through these defects, leading to pitting corrosion. Therefore, reducing internal defects in the DLC film, lowering internal stress, improving film-substrate adhesion, and increasing film density are effective means to improve the corrosion resistance of DLC coatings.

[0003] Plasma-assisted chemical vapor deposition (PECVD) can be used to obtain DLC films with fine structures. However, due to the limited temperature, ion diffusion energy, and small potential difference between the workpiece and the surrounding plasma during the DLC deposition process, high-quality DLC films cannot be obtained using the simple PECVD method.

[0004] To improve the deposition quality of DLC coatings, Wei Ronghua et al. from the Southwest Institute invented a large-area DLC fabrication technique based on mesh hollow cathode discharge and workpiece immersion, called Meshed Plasma Immersion Ion Deposition (MPIID). This technique aims to prepare thick DLC films at a high deposition rate. MPIID technology is based on the hollow cathode effect rather than the traditional glow discharge process. In this method, a metal mesh cage forms a closed space, generating plasma both inside and outside the cage. However, due to the hollow cathode effect, the plasma density inside the cage is much higher than outside, making it suitable for depositing thick DLC films on three-dimensional workpieces. Although MPIID technology offers high plasma density and deposition rate, the energy of ions incident on the sample surface is low and cannot be changed because the sample is located inside the cage and maintains the same potential as the cage.

[0005] To address the above issues, Wu et al. controlled the incident ion energy by applying an additional bias voltage between the sample and the cage, thus obtaining a Si-DLC film with a dense microstructure and low H content. CN201811391383.4 discloses a self-generated cage-shaped hollow cathode structure, such as... Figure 1As shown, a self-sourced hollow cathode discharge method is used to prepare DLC films. The cage is placed directly on the workpiece, and the cage and part or all of the workpiece surface constitute a hollow cathode structure. The workpiece itself also serves as a plasma source (self-sourced), with a gap between the cage and the workpiece. A negative bias voltage is applied to the workpiece relative to the cage to achieve the ion bombardment effect of the film. A high-pulse discharge power supply is used as the excitation power supply for the gas discharge, with the positive terminal connected to the vacuum chamber and the negative terminal connected to the cage. The positive terminal of the bias power supply P2 is connected to the cage, and the negative terminal is connected to the workpiece.

[0006] The cage mesh method can also be used as a cathode for direct deposition of nitride thin films, and the preparation apparatus is as follows: Figure 2 As shown, Dou Ruifen et al. from the Institute of Surface Engineering at Taiyuan University of Technology obtained a relatively dense and uniform tantalum nitride thin film on the surface of carbon steel using a mesh cathode method. The method involves setting up a mesh cathode made of metallic tantalum in a vacuum chamber, with the tantalum sheets maintained at a certain distance to create a hollow cathode effect. This mesh cathode serves as both a dissociation source for the discharge gas and a sputtering source for metal elements. It can sputter out a large number of active tantalum ions, atoms, and atomic groups. When the reactive gas N2 is introduced into the vacuum chamber, the tantalum ions react with the dissociated N ions to synthesize a TaN thin film on the substrate. However, the method of directly synthesizing nitride thin films using the mesh method cannot reliably and stably obtain high-performance continuous nitride thin films; therefore, this method has not yet been industrially applied.

[0007] The cage cathode method can directly prepare DLC films on metal surfaces, and it can also directly deposit nitride films on metal surfaces. However, this method cannot achieve a layer-by-layer transition from metal to DLC film. When preparing DLC ​​coatings on metal, a metal transition layer is an important means to ensure good adhesion between the DLC coating and the substrate. However, the cage cathode method cannot obtain an ideal metal transition layer directly. Directly depositing DLC ​​layers on metal surfaces results in high residual stress during the deposition process, making the film brittle and prone to peeling or detachment in corrosive environments. Currently, titanium and chromium are ideal transition layer metals for preparing DLC ​​coatings on metal substrates. However, substances containing these two elements that can be used as precursor gases are few and have certain limitations. For example, TiCl4, used as a precursor gas for depositing Ti, generates HCl during the deposition process, which has a certain corrosive effect on the deposition equipment and the film. There are currently no reports on ideal precursor gases that can generate metallic Cr. Even if metal elements are obtained through dissociation, the relatively complex atmosphere in the vacuum chamber will still affect the adhesion between the metal elements and the substrate, thus hindering the overall coating performance.

[0008] Furthermore, the above reports only considered the cage mesh's effect as a hollow cathode-like structure in their design and use, thus employing a single-layer cage mesh to achieve ion enhancement through cathode overlap on the mesh openings. However, in reality, besides enhancing the ion discharge of gas through the mesh openings like a hollow cathode, the cage mesh also has a certain filtering function. Additionally, the design of the mesh opening shape and distribution can significantly influence the energy and morphology of the plasma emitted from within, improving the structural density of the DLC film and its adhesion to the substrate.

[0009] In view of the above-mentioned shortcomings of the prior art, the present invention provides an apparatus and method for preparing diamond-like carbon (DLC) films by magnetron sputtering composite PECVD. The metal transition layer is prepared by magnetron sputtering, and larger particles are filtered and the energy of the particles is enhanced after passing through the cage mesh by a gate. This can obtain a DLC film with a dense internal structure and achieve a good transition from the substrate to the DLC coating, thereby achieving the preparation of a DLC film with both good corrosion resistance and abrasion resistance. Summary of the Invention

[0010] The purpose of this invention is to provide an apparatus and method for preparing diamond-like carbon (DLC) films by magnetron sputtering composite PECVD, so as to solve the problems of high interlayer stress, poor corrosion resistance and poor abrasion resistance during DLC ​​coating deposition.

[0011] To address the aforementioned problems, this invention provides an apparatus for preparing diamond-like carbon films using magnetron sputtering composite PECVD, comprising:

[0012] Vacuum chamber, workpiece rack turntable set inside the vacuum chamber, double-layer grid, high-voltage pulse power supply, bias power supply, argon gas input port, and cathode target;

[0013] The double-layer grid includes a screen grid and an acceleration grid. The screen grid is connected to the positive terminal of the high-voltage pulse power supply, and the acceleration grid is connected to the negative terminal of the high-voltage pulse power supply. The double-layer grid is fixedly installed on the workpiece rack turntable. The double-layer grid is insulated from the vacuum chamber, from the screen grid to the acceleration grid, and from the acceleration grid to the workpiece to be plated.

[0014] The positive terminal of the bias power supply is connected to the vacuum chamber, which is grounded. The negative terminal of the bias power supply is connected to the workpiece to be plated. The workpiece to be plated is fixed on the workpiece rack turntable and located inside the double-layer grid.

[0015] The cathode target is located on the side wall of the vacuum chamber and outside the double-layer grid.

[0016] Preferably, it also includes a workpiece hanging rod disposed on the workpiece rack turntable and located inside the double-layer grid, and the workpiece to be plated is fixedly disposed on the workpiece rack turntable by the workpiece hanging rod.

[0017] Preferably, the screen grid and the acceleration grid are coaxially arranged, the acceleration grid is located inside the screen grid, and the distance between the screen grid and the acceleration grid is 10mm to 50mm.

[0018] Preferably, the cross-sections of the screen grid and the acceleration grid are both circular or regular polygonal, and both the screen grid and the acceleration grid have a multi-mesh structure, with the area of ​​the mesh accounting for more than 70% of the grid area.

[0019] Preferably, the mesh size of the screen grid is larger than the mesh size of the acceleration grid, the mesh diameter of the screen grid is 1.5mm to 2.5mm and the thickness is 0.3mm to 1mm, and the mesh diameter of the acceleration grid is 1mm to 1.5mm and the thickness is 0.3mm to 0.8mm.

[0020] In another aspect, the present invention provides a method for preparing diamond-like carbon films by magnetron sputtering combined with PECVD, comprising the following steps:

[0021] S1. Pre-treatment of workpieces: After ultrasonic cleaning and drying, the workpieces to be plated are placed on the workpiece hanging rod in the vacuum chamber.

[0022] S2. Ion beam cleaning: First, the vacuum chamber is evacuated to a vacuum state, then argon gas is introduced, and then the acceleration grid power supply, the screen grid power supply and the bias power supply on the workpiece are turned on in sequence to perform argon ion bombardment cleaning to remove contaminants and oxide layers from the surface of the workpiece to be plated.

[0023] S3. Deposition of bonding layer: Adjust the argon flow rate, turn on the sputtering target power supply, and adjust the sputtering target current and the voltage of the bias power supply to deposit a metal bonding layer on the workpiece after ion beam cleaning.

[0024] S4. Transition layer deposition: Nitrogen gas is introduced, and plasma-enhanced chemical vapor deposition is used to deposit a nitride transition layer on the metal bonding layer. Then, carbon source gas is introduced to deposit a carbonitride transition layer on the nitride transition layer. The transition layer includes a nitride transition layer and a carbonitride transition layer.

[0025] S5, DLC film deposition: Turn off nitrogen gas, adjust the flow rate of the carbon source gas to 40 sccm to 60 sccm, keep the voltage of the bias power supply at -100V, and the deposition time is 120 min to obtain a DLC film.

[0026] Preferably, in step S2, the ion beam cleaning process conditions are as follows: the vacuum degree of the vacuum chamber is 0.001 Pa to 0.004 Pa, the flow rate of argon gas is 100 sccm to 200 sccm, the voltage of the accelerating grid power supply is 200 V, the voltage of the screen grid power supply is 500 V, the voltage of the bias power supply is -400 to 600 V, and the ion beam cleaning time is 15 min to 30 min.

[0027] Preferably, in step S3, the process conditions for depositing the bonding layer are: argon flow rate of 400 sccm to 500 sccm, gas pressure controlled at 0.1 Pa to 0.3 Pa, sputtering target current of 10 A, bias power supply voltage of -100 V, deposition time of 20 min, and the metal bonding layer is a Ti metal layer or a Cr metal layer.

[0028] Preferably, in step S4, the process conditions for depositing the transition layer are as follows: first, adjust the argon flow rate to 200 sccm to 300 sccm, the nitrogen flow rate to 40 sccm, control the gas pressure at 0.08 Pa to 0.1 Pa, maintain the bias power supply voltage at -100 V, and the deposition time is 30 min to obtain a nitride transition layer; then, adjust the argon flow rate to 0 sccm to 100 sccm, the nitrogen flow rate to 10 sccm to 20 sccm, the carbon source gas flow rate to 20 sccm to 40 sccm, control the gas pressure at 0.1 Pa to 0.15 Pa, maintain the bias power supply voltage at -100 V, and the deposition time is 10 min to obtain a carbonitride transition layer. During the deposition process, the voltage of the accelerating grid is -100 V to -200 V, and the voltage of the screen grid is +100 V to +300 V.

[0029] Preferably, the carbon source gas is acetylene or methane, the nitride transition layer is a CrN layer, and the carbonitride transition layer is a CrNC layer.

[0030] In summary, the above-mentioned technical solution of the present invention has the following advantages:

[0031] (1) The present invention utilizes the filtering effect of the double-layer grid structure to reduce the ion deposition rate to a certain extent, thereby refining the deposited ions and increasing the particle deposition energy reaching the substrate. Because the deposited particles have high diffusion energy and low growth stress, the film layer "grows slowly but grows solidly", thus making the prepared DLC film denser, with high bonding force and better corrosion resistance.

[0032] (2) When performing ion cleaning on the workpiece, the dual grid can generate a strong discharge of gas in the vacuum chamber at a lower voltage, providing a high concentration of gas and active substances such as metal ions and atoms to the workpiece space, thereby enhancing the cleaning effect of the workpiece.

[0033] (3) A transition layer is first deposited on the substrate using magnetron sputtering to reduce the mismatch between the physical properties of the DLC coating and the substrate material and reduce the internal stress of the coating. At the same time, plasma-assisted magnetron sputtering can generate high-density plasma in the deposition space, increase the density and energy of bombarding ions on the substrate surface, improve the bonding strength of the DLC film, and increase the dissociation ratio of carbon-containing gas, which is beneficial to the optimization of the internal structure of the DLC film.

[0034] This invention employs a double-layer grid structure composite magnetron sputtering method. A double-layer grid is placed between the magnetron target on the metal wall and the workpiece to be plated, forming a double-grid structure. The grid closest to the magnetron cathode serves as a screen grid, while the grid at a certain distance from the screen grid and closer to the workpiece serves as an acceleration grid. The screen grid acts as the anode of the discharge chamber, absorbing electrons while filtering out some low-energy particles. The charged particles that pass through the screen grid serve as a deposition source and are accelerated by the acceleration grid to have higher energy. These high-energy particles are deposited on the workpiece to form a dense and continuous film layer. Attached Figure Description

[0035] Figure 1 It is an apparatus for preparing DLC ​​coatings using a self-sourced cage-shaped hollow cathode discharge method.

[0036] Figure 2 It is an apparatus for preparing tantalum nitride thin films using the mesh cathode method.

[0037] Figure 3 This is a schematic diagram of the magnetron sputtering device provided by the present invention.

[0038] Figure 4 This is a schematic diagram of the three-dimensional structure of the double-layer grid provided by the present invention.

[0039] Figure 5 This is a schematic diagram of the energy state of ions passing through the gate in the device provided by the present invention.

[0040] Figure 6 This is a schematic diagram of the mesh distribution of the grid provided by the present invention.

[0041] Figure 7 This is a schematic diagram of the grid spacing and mesh design provided by the present invention.

[0042] Figure 8 A diagram showing the surface morphology of the DLC film prepared using a PECVD device.

[0043] Figure 9 The surface morphology of the DLC film prepared by the PECVD apparatus of the double-layer grid of the present invention is shown in the figure.

[0044] Figure 10 Cross-sectional morphology of the DLC film prepared by the PECVD device.

[0045] Figure 11 The image shows the interface morphology of the DLC film prepared by the PECVD apparatus of the double-layer grid of the present invention.

[0046] Figure 12 The self-corrosion potential curve of the DLC film prepared by the PECVD device.

[0047] Figure 13The diagram shows the self-corrosion potential curve of the DLC film prepared by the PECVD device with double-layer grid of the present invention.

[0048] Figure 14 The friction coefficient curves of the DLC film prepared by the PECVD device with double-layer cage mesh of the present invention before and after 600h neutral salt spray corrosion.

[0049] The attached figures are labeled as follows:

[0050] 1. Vacuum chamber, 2. Workpiece rack turntable, 3. Double-layer grid, 4. High-voltage pulse power supply, 5. Bias power supply, 6. Argon gas input port, 7. Cathode target, 8. Screen grid, 9. Acceleration grid, 10. Workpiece hanging rod, 11. Discharge chamber. Detailed Implementation

[0051] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present invention by way of example, but should not be used to limit the scope of the present invention, that is, the present invention is not limited to the described embodiments.

[0052] like Figures 3-4 As shown, the present invention provides an apparatus for preparing diamond-like carbon films by magnetron sputtering composite PECVD, comprising:

[0053] 1. Vacuum chamber, 2. Workpiece rack turntable set in the vacuum chamber, 3. Double-layer grid, 4. High-voltage pulse power supply, 5. Bias power supply, 6. Argon gas input port, and 7. Cathode target;

[0054] The workpiece rack turntable 2 is located at the bottom of the vacuum chamber 1, and the double-layer grid 3 is fixedly installed on the workpiece rack turntable 2. The workpiece to be plated is fixed on the workpiece rack turntable 2 and located inside the double-layer grid 3.

[0055] The double-layer grid 3 includes a screen grid 8 and an acceleration grid 9. The screen grid 8 is connected to the positive terminal of the high-voltage pulse power supply 4, and the acceleration grid 9 is connected to the negative terminal of the high-voltage pulse power supply 4. A discharge chamber 11 is formed between the screen grid 8 and the acceleration grid 9. The double-layer grid 3 is kept insulated from the vacuum chamber 1, the screen grid 8 and the acceleration grid 9, and the acceleration grid 9 and the workpiece to be plated.

[0056] The positive terminal of the bias power supply 5 is connected to the vacuum chamber 1, the vacuum chamber 1 is grounded, and the negative terminal of the bias power supply 5 is connected to the workpiece to be plated. The workpiece to be plated is fixedly set on the workpiece rack turntable 2 and located inside the double-layer grid 3.

[0057] The cathode target 7 is located on the side wall of the vacuum chamber 1 and outside the double-layer grid 3.

[0058] The present invention forms a double-gate structure by setting a double-layer grid 3 between the cathode target 7 and the workpiece to be plated. The layer of grid closer to the cathode target 7 serves as the screen grid 8, which is connected to a positive voltage and serves as the anode of the discharge chamber 11. The layer closer to the workpiece at a certain distance from the screen grid 8 serves as the acceleration grid 9, which is connected to a negative voltage and serves as the cathode of the discharge chamber 11. Therefore, the potential from the screen grid 8 to the acceleration grid 9 is a process from positive to negative.

[0059] During operation, electrons in vacuum chamber 1, under the influence of an electric field, collide with argon atoms as they fly towards the workpiece to be plated, causing the argon atoms to ionize and produce Ar. + And new electrons, new electrons fly toward the workpiece to be plated, Ar + Under the action of the electric field, the particles are accelerated towards the cathode target 7 and bombard the surface of the cathode target 7 with high energy, causing the cathode target to sputter and generate positively charged sputtered particles. When the sputtered particles are accelerated towards the workpiece to be plated, they need to pass through the double-layer grid 3. Since the screen grid 8 is positively charged and the acceleration grid 9 is negatively charged, the positively charged sputtered particles are decelerated to a certain extent when they reach the screen grid 8 under the action of the electric field. Therefore, only sputtered particles that meet a certain energy can pass through the screen grid 8 and enter the discharge chamber 11. After entering the discharge chamber 11, the positively charged sputtered particles are accelerated by the acceleration grid 9 under the action of the electric field and have high energy. These high-energy particles are deposited on the workpiece to form a dense and continuous film layer.

[0060] In other words, the positively charged sputtered particles are first decelerated and then accelerated by the electric field formed by the screen grid 8 and the acceleration grid 9, finally reaching the workpiece surface and forming a good bond with it. The energy change of the particles generated from the cathode target and its surrounding space after passing through the two grids to the workpiece is as follows: Figure 5 As shown.

[0061] As a preferred embodiment, based on the above embodiments, the device further includes workpiece hanging rods 10 disposed on the workpiece rack turntable 2 and located inside the double-layer grid 3. To further improve the deposition rate and deposition quality, multiple workpiece hanging rods 10 are provided and evenly distributed inside the double-layer grid 3.

[0062] Preferably, the screen grid 8 and the acceleration grid 9 are coaxially arranged, the acceleration grid 9 is located inside the screen grid 8, and the distance between the screen grid 8 and the acceleration grid 9 is 10mm to 50mm.

[0063] Preferably, the cross-sections of the screen grid and the acceleration grid are both circular or regular polygonal; more preferably, the cross-sections of the screen grid and the acceleration grid are both circular.

[0064] Preferably, the screen grid and the acceleration grid have a multi-mesh structure, and the area of ​​the mesh accounts for more than 70% of the grid area.

[0065] It should be noted that, in order to improve the efficiency of the grid in extracting sputtered particles, the distribution design of the grid apertures is as follows: Figure 6 As shown, the electric field of the curved emitting surface converges the ion beam before it enters the accelerating grid, resulting in a generally conical beam shape. Due to the aperture limitations of the apertures on the screen and accelerating grids, and the divergence of space charge, a waist appears in the spatial channel formed by the two grid apertures. Preferably, the waist of the ion beam is located in the middle of the ion channel between the two grid layers, so that the plasma just barely brushes past the entrance of the screen aperture and the exit of the accelerating grid aperture. Obviously, this minimizes the number of ions hitting the inner walls of the apertures and the grid surface, resulting in the highest ion extraction efficiency.

[0066] Preferably, the mesh size of the screen grid is larger than the mesh size of the acceleration grid, the mesh diameter of the screen grid is 1.5mm to 2.5mm and the thickness is 0.3mm to 1mm, and the mesh diameter of the acceleration grid is 1mm to 1.5mm and the thickness is 0.3mm to 0.8mm.

[0067] The grid spacing and mesh design of this invention are as follows: Figure 7 As shown, while the use of a double-layer grid electrode inevitably reduces the number of ions reaching the workpiece, it is precisely this filtering effect that allows some high-energy ions to reach the workpiece surface. These particles have strong migration capabilities. Although the number of ions reaching the workpiece surface is affected, the DLC film deposited on the surface has more migration and growth time, reducing growth defects and resulting in a denser film structure and better surface quality. Consequently, the prepared DLC film exhibits high corrosion resistance.

[0068] In addition, the negative ions in the magnetron sputtering products are attracted by the grid, causing their trajectory to be deflected. The angle of deflection towards the grid is small, and some of them will reach the substrate through the mesh and undergo chemical reactions on its surface. As for the electrons with smaller mass, most of them are deflected onto the grid and discharged through grounding, thereby reducing the internal defects of the thin film caused by electron bombardment and reducing its surface roughness.

[0069] In another aspect, the present invention provides a method for preparing diamond-like carbon films by magnetron sputtering combined with PECVD, comprising the following steps:

[0070] S1. Pre-treatment of workpieces: After ultrasonic cleaning and drying, the workpieces to be plated are placed on the workpiece hanging rod in the vacuum chamber.

[0071] S2. Ion beam cleaning: First, the vacuum chamber is evacuated to a vacuum state, then argon gas is introduced, and then the acceleration grid power supply, the screen grid power supply and the bias power supply on the workpiece are turned on in sequence to perform argon ion bombardment cleaning to remove contaminants and oxide layers from the surface of the workpiece to be plated.

[0072] Preferably, the ion beam cleaning process conditions are as follows: the vacuum degree of the vacuum chamber is 0.001 Pa to 0.004 Pa, the flow rate of argon gas is 100 sccm to 200 sccm, the voltage of the accelerating grid power supply is 200 V, the voltage of the screen grid power supply is 500 V, the voltage of the bias power supply is -400 to 600 V, and the ion beam cleaning time is 15 min to 30 min.

[0073] S3. Deposition of bonding layer: Adjust the argon flow rate, turn on the sputtering target power supply, and adjust the sputtering target current and bias power supply voltage to deposit a metal bonding layer on the workpiece after ion beam cleaning.

[0074] Preferably, the process conditions for depositing the bonding layer are: argon flow rate of 400 sccm to 500 sccm, gas pressure controlled at 0.1 Pa to 0.3 Pa, sputtering target current of 10 A, bias power supply voltage of -100 V, and deposition time of 20 min. The metal bonding layer is a Ti metal layer or a Cr metal layer.

[0075] S4. Transition layer deposition: Nitrogen gas is introduced, and plasma-enhanced chemical vapor deposition is used to deposit a nitride transition layer on the metal bonding layer. Then, carbon source gas is introduced to deposit a carbonitride transition layer on the nitride transition layer. The transition layer includes a nitride transition layer and a carbonitride transition layer.

[0076] Preferably, the process conditions for depositing the transition layer are as follows: first, adjust the argon flow rate to 200 sccm to 300 sccm, the nitrogen flow rate to 40 sccm, control the gas pressure to 0.08 Pa to 0.1 Pa, maintain the bias voltage at -100 V, and deposit for 30 min to obtain a nitride transition layer; then, adjust the argon flow rate to 0 sccm to 100 sccm, the nitrogen flow rate to 10 sccm to 20 sccm, the carbon source gas flow rate to 20 sccm to 40 sccm, control the gas pressure to 0.1 Pa to 0.15 Pa, maintain the bias voltage at -100 V, and deposit for 10 min to obtain a carbonitride transition layer. During the deposition process, the voltage of the accelerating grid is -100 V to -200 V, and the voltage of the screen grid is +100 V to +300 V.

[0077] S5, DLC film deposition: Turn off nitrogen gas, adjust the flow rate of the carbon source gas to 40 sccm to 60 sccm, keep the bias voltage at -100V, and the deposition time is 120 min to obtain a DLC film.

[0078] Example 1

[0079] 1. Pre-cleaning process of parts

[0080] Place the workpiece to be plated in an acetone solution, put it in an ultrasonic cleaning test machine for 30 minutes, then dry it with a hair dryer, put it in an alcohol solution, put it in an ultrasonic cleaning machine for 30 minutes, and finally dry it with a hair dryer.

[0081] 2. Installation of magnetron sputtering device

[0082] Mount the screen grid and acceleration grid onto the workpiece rack turntable, and check the insulation between them and between the double-layer grid and the vacuum chamber, ensuring that the double-layer grid is insulated from the vacuum chamber. Check the connection between the cage mesh and the power supply; connect the screen grid to the positive electrode and the acceleration grid to the negative electrode.

[0083] 3. Ion beam cleaning

[0084] Place the dried workpiece to be plated on the workpiece hanger in the vacuum chamber of the equipment, and close the vacuum chamber. Turn on the vacuum generating device to evacuate the vacuum to 0.001 Pa to 0.004 Pa. Introduce argon gas, adjusting the argon flow rate to between 0 and 200 sccm and the gas pressure to between 0.05 Pa and 0.08 Pa. Turn on the power supply of the accelerating grid, adjusting the accelerating grid power supply voltage to 200V and the screen grid power supply to 500V. Turn on the bias power supply on the workpiece, setting the voltage to -400 to 600V, and perform argon ion bombardment cleaning, controlling the cleaning time to between 15 min and 30 min.

[0085] 4. Preparation of the bonding layer

[0086] Adjust the argon flow rate to between 400 and 500 sccm, control the gas pressure between 0.1 Pa and 0.3 Pa, turn on the magnetron sputtering target power supply, keep the workpiece to be plated rotating, adjust the Cr target current to 10 A, adjust the bias voltage of the bias system to -100 V, and the deposition time to 20 min to obtain the Cr layer; keep the double-layer grid power supply on during the preparation process.

[0087] 5. Preparation of the load-bearing and transition layer

[0088] The argon flow rate was adjusted to between 200 sccm and 300 sccm, the nitrogen flow rate to 40 sccm, and the gas pressure controlled between 0.08 Pa and 0.1 Pa. The target distance remained constant, the Cr target current was maintained at 8 A, and the bias power supply voltage was maintained at -100 V. The deposition time was 30 min to prepare a CrN layer. Subsequently, the argon flow rate was adjusted to between 0 and 100 sccm, the nitrogen flow rate to 10 sccm and 20 to 40 sccm, and the gas pressure controlled between 0.1 and 0.15 Pa. The target distance remained constant, the Cr target current was maintained at 8 A, and the bias power supply voltage was maintained at -100 V. The deposition time was 10 min to prepare a CrNC layer.

[0089] 6. Preparation of DLC films

[0090] Turn off argon and nitrogen, adjust the acetylene gas flow rate to 40 sccm to 60 sccm, control the gas pressure between 0.1 and 0.15 Pa, keep the target distance unchanged, uniformly adjust the Cr target current to 0 A within 15 min, keep the bias power supply voltage at -100 V, and the deposition time is 120 min to prepare the DLC layer.

[0091] The performance of DLC films prepared by the device with added double-layer grids and the device without double-layer grids was compared in an experiment. The results are as follows:

[0092] Figure 8 The surface morphology of the DLC film prepared by the PECVD device was obtained. Figure 9 To improve the surface morphology of DLC films prepared using a PECVD apparatus with a double-layer grid, from... Figure 8 and Figure 9 It can be seen that the DLC film prepared by adding a double-layer grid to the PECVD device has a denser surface.

[0093] Figure 10 The cross-sectional morphology of the DLC film prepared by the PECVD device was obtained. Figure 11 To improve the interface morphology of DLC films prepared using a PECVD device with a double-layer grid, from... Figure 10 and Figure 11 It can be seen that the DLC film prepared by adding a double-layer grid has a better direct bonding interface and achieves a good transition between film layers, indicating that the film quality is better.

[0094] Figure 12 The self-corrosion potential curve of the DLC film prepared by the PECVD device. Figure 13 To obtain the self-corrosion potential curve of the DLC film prepared by the PECVD device with added double-layer grid, from... Figure 12 and Figure 13 It can be seen that the self-corrosion potential of the DLC film prepared by the PECVD device is 0.23V, and the corrosion current density is 8×10⁻⁶. -6 A. The DLC film prepared by the PECVD device with added double-layer grid has a self-corrosion potential of 0.23V and a corrosion current density of 4×10⁻⁶. -9 A indicates that the DLC film prepared by adding a double-layer grid to the PECVD device has better corrosion resistance.

[0095] Figure 14 The graph shows the friction coefficient curves of the DLC film before and after 600h neutral salt spray corrosion after adding a double-layer grid. The graph shows that the DLC film prepared by adding a double-layer grid has better friction resistance.

[0096] In summary, the present invention provides a DLC film preparation apparatus and method. The present invention uses a PECVD apparatus with a double-layer grid. First, a metal transition layer is prepared by magnetron sputtering, which realizes a good transition from the substrate to the DLC coating. Combined with the double-layer grid structure, a dense DLC film layer is obtained, thereby realizing the preparation of a DLC film layer with good corrosion resistance and abrasion resistance.

[0097] It should be clarified that the present invention is not limited to the specific steps and structures described above and shown in the figures. Furthermore, for the sake of brevity, detailed descriptions of known methods and techniques are omitted here.

[0098] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art without departing from the scope of the invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this application should be included within the scope of the claims of this application.

Claims

1. An apparatus for preparing diamond-like carbon films by magnetron sputtering combined with PECVD, characterized in that: It includes a vacuum chamber, a workpiece rack turntable installed inside the vacuum chamber, a double-layer grid, a high-voltage pulse power supply, a bias power supply, an argon gas input port, and a cathode target; The double-layer grid includes a screen grid and an acceleration grid. The screen grid is connected to the positive terminal of the high-voltage pulse power supply, and the acceleration grid is connected to the negative terminal of the high-voltage pulse power supply. The double-layer grid is fixedly installed on the workpiece rack turntable. The double-layer grid is insulated from the vacuum chamber, from the screen grid to the acceleration grid, and from the acceleration grid to the workpiece to be plated. The positive terminal of the bias power supply is connected to the vacuum chamber, which is grounded. The negative terminal of the bias power supply is connected to the workpiece to be plated. The workpiece to be plated is fixed on the workpiece rack turntable and located inside the double-layer grid. The cathode target is located on the side wall of the vacuum chamber and outside the double-layer grid. In this process, the grid acts as the anode of the discharge chamber, absorbing electrons while filtering out some low-energy particles. The charged particles that pass through the grid act as a deposition source and are accelerated by the acceleration grid to have higher energy. These high-energy particles are deposited on the workpiece to form a dense and continuous film.

2. The apparatus according to claim 1, characterized in that: It also includes a workpiece hanging rod set on the workpiece rack turntable and located inside the double-layer grid. The workpiece to be plated is fixedly set on the workpiece rack turntable by the workpiece hanging rod.

3. The apparatus according to claim 1, characterized in that: The screen grid and the acceleration grid are coaxially arranged, with the acceleration grid located inside the screen grid, and the distance between the screen grid and the acceleration grid is 10mm to 50mm.

4. The apparatus according to claim 2, characterized in that: Both the screen grid and the acceleration grid have circular or regular polygonal cross-sections, and both have multi-mesh structures, with the area of ​​the mesh accounting for more than 70% of the grid area.

5. The apparatus according to claim 3, characterized in that: The mesh size of the screen grid is larger than that of the acceleration grid. The mesh diameter of the screen grid is 1.5mm to 2.5mm and the thickness is 0.3mm to 1mm. The mesh diameter of the acceleration grid is 1mm to 1.5mm and the thickness is 0.3mm to 0.8mm.

6. A method for preparing diamond-like carbon films by magnetron sputtering combined with PECVD, characterized in that: The method is carried out using the apparatus for preparing diamond-like carbon films by magnetron sputtering composite PECVD as described in any one of claims 1-5, and includes the following steps: S1. Pre-treatment of workpieces: After ultrasonic cleaning and drying, the workpieces to be plated are placed on the workpiece hanging rod in the vacuum chamber. S2. Ion beam cleaning: First, the vacuum chamber is evacuated to a vacuum state, then argon gas is introduced, and then the acceleration grid power supply, the screen grid power supply and the bias power supply on the workpiece are turned on in sequence to perform argon ion bombardment cleaning to remove contaminants and oxide layers from the surface of the workpiece to be plated. S3. Deposition of bonding layer: Adjust the argon flow rate, turn on the sputtering target power supply, and adjust the sputtering target current and the voltage of the bias power supply to deposit a metal bonding layer on the workpiece after ion beam cleaning. S4. Transition layer deposition: Nitrogen gas is introduced, and plasma-enhanced chemical vapor deposition is used to deposit a nitride transition layer on the metal bonding layer. Then, carbon source gas is introduced to deposit a carbonitride transition layer on the nitride transition layer. The transition layer includes a nitride transition layer and a carbonitride transition layer. S5, DLC film deposition: Turn off nitrogen gas, adjust the flow rate of the carbon source gas to 40 sccm to 60 sccm, keep the voltage of the bias power supply at -100V, and the deposition time is 120 min to obtain a DLC film.

7. The method according to claim 6, characterized in that: In step S2, the ion beam cleaning process conditions are as follows: the vacuum degree of the vacuum chamber is 0.001 Pa to 0.004 Pa, the flow rate of argon gas is 100 sccm to 200 sccm, the voltage of the accelerating grid power supply is 200 V, the voltage of the screen grid power supply is 500 V, the voltage of the bias power supply is -400 to 600 V, and the ion beam cleaning time is 15 min to 30 min.

8. The method according to claim 6, characterized in that: In step S3, the process conditions for depositing the bonding layer are as follows: argon flow rate of 400 sccm to 500 sccm, gas pressure controlled at 0.1 Pa to 0.3 Pa, sputtering target current of 10 A, bias power supply voltage of -100 V, deposition time of 20 min, and the metal bonding layer is a Ti metal layer or a Cr metal layer.

9. The method according to claim 6, characterized in that: In step S4, the process conditions for depositing the transition layer are as follows: First, adjust the argon flow rate to 200 sccm to 300 sccm, the nitrogen flow rate to 40 sccm, control the gas pressure at 0.08 Pa to 0.1 Pa, maintain the bias power supply voltage at -100 V, and the deposition time is 30 min to obtain a nitride transition layer; then adjust the argon flow rate to 0 sccm to 100 sccm, the nitrogen flow rate to 10 sccm to 20 sccm, the carbon source gas flow rate to 20 sccm to 40 sccm, control the gas pressure at 0.1 Pa to 0.15 Pa, maintain the bias power supply voltage at -100 V, and the deposition time is 10 min to obtain a carbonitride transition layer. During the deposition process, the voltage of the accelerating grid is -100 V to -200 V, and the voltage of the screen grid is +100 V to +300 V.

10. The method according to claims 6-9, characterized in that: The carbon source gas is acetylene or methane, the nitride transition layer is a CrN layer, and the carbonitride transition layer is a CrNC layer.

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