A carbon-based heterogeneous coating film and a method for producing the same

Abstract

The present application relates to a carbon-based heterogeneous coating film and a preparation method thereof. The carbon material in the present application has abundant structural forms, including graphite phase, diamond phase and amorphous carbon phase. Among them, the graphite phase generally has relatively high electrical conductivity, while the diamond phase and the amorphous carbon phase can change the transport path of carriers. Therefore, the electrical properties of the carbon-based material can be changed by adjusting the proportion of different carbon phases.

Description

Technical Field

[0001] This application belongs to the field of functional coating materials technology, and in particular relates to a carbon-based multiphase coating film and its preparation method. Background Technology

[0002] In microelectronic devices, precision instruments, high-end electrical equipment, and conductive contact components, it is often necessary to obtain predetermined resistance characteristics within a limited size and thickness range. The resistance of coating materials is not only related to their own resistivity but is also affected by factors such as coating thickness, length, width, and testing methods. Traditional metal thin films typically have good conductivity, but their electrical performance control mainly depends on the type of metal, film thickness, and structural dimensions, making it difficult to simultaneously achieve a range of resistance adjustment, stability, and microstructure designability.

[0003] Chinese patent CN106505046B discloses a carbon-aluminum-carbon semiconductor thin film material with an insulating substrate and its preparation method. This technology employs a sandwich structure of carbon film / aluminum intercalation / carbon film, wherein the thickness of each of the two carbon films is 20–80 nm, and the thickness of the aluminum intercalation layer is 8 nm. The resistivity of the carbon-aluminum-carbon sandwich thin film disclosed in this patent is 2.7 × 10⁻⁶. - The resistivity of carbon films is 3 Ω•cm, while that of pure carbon films is 5.1×10² Ω•cm, indicating that continuous aluminum intercalation can significantly reduce the resistivity of carbon films. However, this technology uses continuous aluminum intercalation layers of fixed thickness, mainly achieving carrier injection and transport improvement through the sandwich structure, making it difficult to achieve designable adjustment of the resistance parameters of carbon-based composite coatings. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a carbon-based multiphase coating film and its preparation method in order to overcome the shortcomings of the prior art.

[0005] The technical solution adopted by this invention to solve its technical problem is: A carbon-based multiphase coating film includes a carbon matrix, wherein the carbon matrix contains 90% to 96% amorphous carbon phase, 3.1% to 8.8% graphite phase, and 1.2% to 1.5% diamond phase by volume.

[0006] Preferably, in the carbon-based multiphase coating film of the present invention, the average grain size of the amorphous carbon phase is 9.6~14.4 nm; the average grain size of the graphite phase is 8.7~17.2 nm; and the average grain size of the diamond phase is 9.9~13.0 nm.

[0007] Preferably, the carbon-based multiphase coating film of the present invention further includes a metallic conductive phase, wherein the metallic conductive phase is at least one of gold, silver, copper, platinum or an alloy.

[0008] Preferably, in the carbon-based multiphase coating film of the present invention, the metallic conductive phase is distributed in the carbon matrix in the form of particles, clusters, islands, discontinuous networks, or continuous networks.

[0009] This invention also provides a method for preparing carbon-based multiphase coated thin films, comprising the following steps: S1. Clean, dry and pre-treat the substrate; S2. Provide a carbon source, wherein the carbon source is a graphite target; S3. In a vacuum deposition environment, a carbon-based multiphase coating film is formed on the surface of the substrate by deposition.

[0010] Preferably, in the method for preparing the carbon-based multiphase coating film of the present invention, the graphite target power is 200W-500W and the substrate temperature is 200℃-300℃.

[0011] Preferably, the method for preparing the carbon-based multiphase coating film of the present invention, A metal target is also provided in step S2; in step S3, the graphite target and the metal target are co-sputtered.

[0012] Preferably, in the method for preparing the carbon-based multiphase coating film of the present invention, the metal target is a platinum target, and the power of the platinum target is 50W-100W.

[0013] Preferably, in the method for preparing the carbon-based multiphase coating film of the present invention, the substrate is one or more of copper, iron, gold, silver, FeCrNi alloy and their alloys.

[0014] Preferably, the method for preparing the carbon-based multiphase coating film of the present invention controls the relative content of graphite phase, diamond phase, and amorphous carbon phase in the carbon matrix by adjusting the substrate temperature and / or carbon source power; controls the metal content in the carbon matrix by adjusting the substrate temperature and / or metal source power; and adjusts the film thickness by controlling the sputtering time. A carbon-based multiphase coating film with the desired total resistance and resistivity is obtained.

[0015] The beneficial effects of this invention are: The carbon materials in the carbon-based multiphase coating films of this invention possess diverse structural forms, including graphite phase, diamond phase, and amorphous carbon phase. Among these, the graphite phase (sp2-rich carbon phase) typically exhibits relatively high electrical conductivity, while the diamond phase (sp3-rich carbon phase) and amorphous carbon phase can alter the transport paths of charge carriers. Therefore, the electrical properties of carbon-based materials can be modified by adjusting the proportions of different carbon phases.

[0016] This application presents a designable micro-ohm resistance control platform: through three independent and synergistic control paths of carbon phase composition, metal doping, and thickness, it enables precise design within a resistance range of up to six orders of magnitude, while being compatible with various industrial-grade deposition processes, covering application needs across multiple scenarios from precision electronic components to large conductive parts.

[0017] Applications of carbon-based multiphase coated thin film materials cover: Precision resistors: enable wide-range adjustment across orders of magnitude, and can be used as fixed-value resistive elements in precision instruments.

[0018] Conductive contact components: relay contacts and switch contacts, which combine conductivity and wear-resistant carbon layer protection.

[0019] Microelectronic interconnects: Low-resistivity interconnect layers and contact electrodes, Pt-doped coatings have natural compatibility in the microelectronics field.

[0020] Electrode functional layer: surface modification of sensor electrodes and electrochemical electrodes.

[0021] Precision electrical materials: any functional coating that requires precise control of resistance values. Attached Figure Description

[0022] The technical solution of this application will be further described below with reference to the accompanying drawings and embodiments.

[0023] Figure 1 This is a schematic diagram of the structure of the carbon-based multiphase coating film in Embodiment 1 of the present invention.

[0024] Figure 2 The image shows the XRD pattern of the carbon-based multiphase coating film in Example 1 of this invention.

[0025] Figure 3 The images show the surface SEM image and EDS elemental distribution diagram of the carbon-based multiphase coating film in Example 1 of the present invention. (a) is the surface SEM image, and (b) is the C elemental distribution diagram.

[0026] Figure 4 The images shown are SEM images and EDS elemental distribution diagrams of the metal-doped carbon-based multiphase coating film in Example 7 of the present invention. (a) is the surface SEM image, (b) is the C elemental distribution diagram, and (c) is the Pt elemental distribution diagram.

[0027] Figure 5 The cross-sectional SEM image and EDS elemental distribution map of the carbon-based multiphase coating film in Example 1 of this invention are shown in the following figures: (a) is the surface SEM image, (b) is the Cu elemental distribution map, (c) is the C elemental distribution map, (d) is the Fe elemental distribution map, (e) is the Cr elemental distribution map, and (f) is the Cr elemental distribution map.

[0028] Figure 6This is a graph showing the change in resistance of the coated thin film as a function of the metal target power or the amount of metal doping in an embodiment of the present invention.

[0029] Figure 7 This is a graph showing the change in coating film thickness with metal target power or metal doping amount in an embodiment of the present invention.

[0030] Figure 8 This is a graph showing the change in resistivity of the coating film as a function of metal target power or metal doping amount in an embodiment of the present invention.

[0031] Figure 9 The image shows the XRD pattern of the coating film in Comparative Example 1. Detailed Implementation

[0032] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0033] Example 1 This embodiment provides a method for preparing a carbon-based multiphase coating thin film, the specific steps of which are as follows: FeCrNi metal sheets were selected as the substrate. The substrate was first subjected to ultrasonic cleaning and drying.

[0034] The cleaned FeCrNi metal sheet was placed in the vacuum chamber of the magnetron sputtering equipment, and the vacuum level was evacuated to 5 × 10⁻⁶. -4 Pa.

[0035] A high-purity graphite target was used as the carbon source. Under an argon atmosphere, the graphite target power supply was turned on for pre-sputtering, which lasted for 5 minutes to remove contaminants from the target surface and stabilize the sputtering state.

[0036] Then, sputtering was performed using a graphite target with a power of 200 W, a substrate temperature of 300 °C, and a deposition time of 1.5 h.

[0037] After sedimentation, such as Figure 1 A carbon-based multiphase coating film with a thickness of approximately 20 μm was obtained on the surface of an FeCrNi metal sheet.

[0038] The obtained coating was subjected to XRD test to determine the carbon phase composition; the coating cross-sectional morphology, film thickness and elemental distribution were tested by SEM and EDS; the resistance was measured by the four-probe method and the resistivity was calculated based on the film thickness.

[0039] The XRD results showed that the proportion of graphite phase was 5.8%, the proportion of diamond carbon phase was 1.3%, and the proportion of amorphous carbon phase was 92.9%. In terms of grain size, the amorphous carbon phase was 13.0±0.2 nm, the graphite phase was 14.5±0.7 nm, and the diamond carbon phase was 12.1±3.3 nm.

[0040] The coating thickness was 20.78 ± 0.42 μm. The total resistivity of the carbon-based multiphase coating was measured to be 110 ± 3.54 μΩ using the four-probe method, and the calculated resistivity was (2.20 ± 0.04) × 10^ -6 The resistance value is Ω·cm, indicating that the coating can achieve stable resistance control at the level of hundreds of microohms.

[0041] Example 2 This embodiment provides a method for preparing a carbon-based multiphase coating thin film, the specific steps of which are as follows: The process is basically the same as in Example 1, except that the graphite target power is 200 W, the substrate temperature is 300 °C, and the deposition time is 700 s.

[0042] XRD results showed that the proportion of graphite phase was 3.1%, the proportion of diamond carbon phase was 1.2%, and the proportion of amorphous carbon phase was 95.7%. In terms of grain size, the amorphous carbon phase was 9.6±0.3 nm, the graphite phase was 8.7±0.8 nm, and the diamond carbon phase was 9.9±2.4 nm.

[0043] The coating thickness is approximately 2.69 ± 0.05 μm. The total resistivity of the carbon-based multiphase coating, measured using the four-probe method, is 15 ± 0.48 μΩ. Based on the same test geometry, the resistivity is calculated to be (3.89 ± 0.08) × 10^ -8 Ω·cm. This indicates that even with a shortened deposition time, the coating can still achieve low resistance characteristics on the order of ten microohms.

[0044] Example 3 This embodiment provides a method for preparing a carbon-based multiphase coating thin film, the specific steps of which are as follows: The process is basically the same as in Example 1, except that the graphite target power is 200 W, the substrate temperature is 300 °C, and the deposition time is 3 h.

[0045] XRD results showed that the proportion of graphite phase was 7.1%, diamond carbon phase was 1.4%, and amorphous carbon phase was 91.5%. In terms of grain size, the amorphous carbon phase was 14.4±0.3 nm, the graphite phase was 17.2±0.9 nm, and the diamond carbon phase was 13.0±2.8 nm.

[0046] The coating thickness is approximately 41.56 ± 0.84 μm. The total resistivity of the carbon-based multiphase coating, measured using the four-probe method, is 226 ± 7.43 μΩ, and the calculated resistivity is (9.04 ± 0.18) × 10^ -6 Ω·cm. This indicates that by extending the deposition time, an adjustable resistance on the order of hundreds of microohms can be obtained.

[0047] Example 4 This embodiment provides a method for preparing a carbon-based multiphase coating thin film, the specific steps of which are as follows: The process is basically the same as in Example 1, except that the graphite target power is 500 W, the substrate temperature is 200 °C, and the deposition time is 1.5 h.

[0048] XRD results showed that the proportion of graphite phase was 3.4%, diamond carbon phase was 1.4%, and amorphous carbon phase was 95.2%. In terms of grain size, the amorphous carbon phase was 11.5±0.3 nm, the graphite phase was 11.9±0.8 nm, and the diamond carbon phase was 11.2±2.6 nm.

[0049] The coating thickness is approximately 51.95 ± 1.05 μm. The total resistivity of the carbon-based multiphase coating, measured using the four-probe method, is 1070 ± 27.78 μΩ, or approximately 1.07 mΩ. The calculated resistivity is (5.35 ± 0.11) × 10^ -5 Ω·cm. This indicates that by increasing the graphite target power to 500 W, a carbon-based coating with higher resistance can be obtained.

[0050] Example 5 This embodiment provides a method for preparing a carbon-based multiphase coating thin film, the specific steps of which are as follows: The process is basically the same as in Example 1, except that the graphite target power is 400 W, the substrate temperature is 300 °C, and the deposition time is 1.5 h.

[0051] XRD results showed that the proportion of graphite phase was 3.8%, the proportion of diamond carbon phase was 1.4%, and the proportion of amorphous carbon phase was 94.8%. In terms of grain size, the amorphous carbon phase was 11.9±0.3 nm, the graphite phase was 12.5±0.8 nm, and the diamond carbon phase was 11.5±2.7 nm.

[0052] The coating thickness is approximately 41.56 ± 0.84 μm. The total resistivity of the carbon-based multiphase coating, measured using the four-probe method, is 874 ± 29.94 μΩ, and the calculated resistivity is (3.50 ± 0.07) × 10^ -5 Ω·cm indicates that near-milliohm-level resistance adjustment can be achieved at a graphite target power of 400 W.

[0053] Example 6 This embodiment provides a method for preparing a carbon-based multiphase coating thin film, the specific steps of which are as follows: The process is basically the same as in Example 1, except that the graphite target power is 300 W, the substrate temperature is 300 °C, and the deposition time is 1.5 h.

[0054] XRD results showed that the proportion of graphite phase was 4.6%, the proportion of diamond carbon phase was 1.3%, and the proportion of amorphous carbon phase was 94.1%. In terms of grain size, the amorphous carbon phase was 12.3±0.3 nm, the graphite phase was 13.3±0.8 nm, and the diamond carbon phase was 11.7±2.8 nm.

[0055] The coating thickness is approximately 31.17 ± 0.63 μm. The total resistivity of the carbon-based multiphase coating, measured using the four-probe method, is 563 ± 15.24 μΩ, and the calculated resistivity is (1.69 ± 0.03) × 10^ -5 Ω·cm. This indicates that resistance control on the order of hundreds of microohms can be achieved under these conditions.

[0056] Example 7 This embodiment provides a method for preparing a platinum-doped carbon-based multiphase coating thin film, the specific steps of which are as follows: FeCrNi metal sheets were selected as the substrate. The substrate was first subjected to ultrasonic cleaning and drying.

[0057] The cleaned FeCrNi metal sheet was placed in the vacuum chamber of the magnetron sputtering equipment, and the vacuum level was evacuated to 5 × 10⁻⁶. -4 Pa.

[0058] A high-purity graphite target was used as the carbon source, and a platinum target as the metal source. Under an argon atmosphere, the graphite target power supply was turned on for pre-sputtering for 5 minutes to remove contaminants from the target surface and stabilize the sputtering state.

[0059] Subsequently, co-sputtering was performed using a graphite target and a platinum target, with the graphite target power at 200 W and the platinum target power at 50 W, the substrate temperature at 300 ℃, and the deposition time at 1.5 h.

[0060] The surface morphology and platinum distribution of the coating were tested using SEM and EDS. The sheet resistance was measured using the four-probe method, and the resistivity was calculated based on the film thickness.

[0061] XRD results show that the carbon phase comprises 7.4% graphite, 1.5% diamond, and 91.1% amorphous carbon. In terms of grain size, the amorphous carbon phase is approximately 12.4 nm, the graphite phase is approximately 16.0 nm, and the diamond phase is approximately 11.7 nm. The Pt element content is approximately 3.2 ± 0.5 at.%, with an average Pt metallic phase grain size of approximately 5.6 ± 0.8 nm, distributed in nanoparticles and island structures within the carbon matrix.

[0062] The coating thickness is approximately 21.82 ± 0.44 μm. The total resistivity of the platinum-doped carbon-based multiphase coating, measured using the four-probe method, is 3 ± 0.13 μΩ, and the resistivity is (6.30 ± 0.13) × 10⁻⁶.-8 Ω·cm. This indicates that the Pt nanoparticles form island-like or locally interconnected conductive pathways in the carbon matrix, which can reduce the coating resistance to the range of a few microohms.

[0063] Example 8 This embodiment provides a method for preparing a platinum-doped carbon-based multiphase coating thin film, the specific steps of which are as follows: Similar to Example 1, co-sputtering was performed on a graphite target and a platinum target, with the graphite target power being 200 W, the platinum target power being 100 W, the substrate temperature being 300 °C, and the deposition time being 1.5 h.

[0064] XRD results showed that the proportion of graphite phase was 8.5%, diamond phase was 1.5%, and amorphous carbon phase was 90.0%. In terms of grain size, the amorphous carbon phase was approximately 12.0 nm, the graphite phase was approximately 16.6 nm, and the diamond phase was approximately 11.6 nm. The Pt element content was 6.1 ± 0.8 at.%, and the average grain size of the Pt metallic phase was approximately 8.0 ± 1.0 nm. With increasing Pt target power, the number of Pt nanoparticles increased, the interparticle spacing decreased, and a more pronounced discontinuous network-like conductive structure was formed.

[0065] The coating thickness is approximately 22.86 ± 0.97 μm. The total resistivity of the platinum-doped carbon-based multiphase coating, measured using the four-probe method, is 1 ± 0.04 μΩ, and the calculated resistivity is (2.20 ± 0.09) × 10^ -8 Ω·cm indicates that increasing the Pt target power improves the number and connectivity of Pt particles, resulting in a low-resistance coating on the order of microohms.

[0066] This patent introduces a metallic conductive phase into a carbon-based coating, forming two complementary electron transport channels: Carbon phase pathways: The graphite phase (highly conductive sp² structure) provides the basic low-resistivity pathway, while the amorphous carbon phase and diamond phase modulate the carrier scattering path. Metallic phase channels: Pt, Ag, Cu and other metal nanoparticles / clusters / networks provide additional low-resistance pathways, and the distribution morphology of the metallic phase (granular → island-like → discontinuous network → continuous network) directly affects the connectivity of these pathways. The two channels work together to reduce the resistivity from 10 in pure carbon-based materials. -6 The Ω·cm level drops to 10 after metal doping. -8 This represents a leap in resistivity, reaching the order of magnitude of Ω·cm, and thus further expanding the range of resistivity control.

[0067] When it is necessary to obtain a carbon-based multiphase coating film with the required total resistance and resistivity, the relationship between total resistance and resistivity and substrate temperature, carbon source power and metal source power (when a metal source is present, such as Pt) and the relative contents of graphite phase, diamond phase and amorphous carbon phase in the carbon matrix, as well as the metal content in the carbon matrix, can be established experimentally; the relationship between sputtering time and film thickness can also be established. Then, based on the above relationships, the relative contents of the graphite phase, diamond phase, and amorphous carbon phase in the carbon matrix can be controlled by adjusting the substrate temperature and / or the carbon source power; the metal content in the carbon matrix can be controlled by adjusting the substrate temperature and / or the metal source power; and the film thickness can be adjusted by controlling the sputtering time; so as to obtain a carbon-based multiphase coating film with the required total resistance and resistivity.

[0068] Comparative Examples 1-4 Comparative Examples 1-4 used the same substrate cleaning method, background vacuum level, and argon atmosphere as Example 1, with the only differences being the graphite target power, substrate temperature, and deposition time.

[0069] The graphite target power, substrate temperature, and deposition time are shown in Table 1.

[0070] Table 1 shows the graphite target power, substrate temperature, and deposition time for different comparative examples.

[0071] Table 2 Total resistance, thickness, resistivity, and phase composition of different comparative examples

[0072] In Comparative Examples 2-4, the remaining phases were all amorphous carbon phases.

[0073] The average grain size of the graphite phase in Comparative Example 1 is 20.80 nm. The average grain size of the graphite phase in Comparative Example 2 is 21.60 nm. The average grain size of the graphite phase in Comparative Example 3 is 22.40 nm. The average grain size of the graphite phase in Comparative Example 4 is 23.10 nm.

[0074] As can be seen, the coating film obtained at low graphite target power is almost a single graphite phase. The embodiments of this application achieve wide-range tunability and stability through three paths: "multiphase composition + metal doping + thickness".

[0075] Based on the above-described preferred embodiments according to this application, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the technical concept of this application. The technical scope of this application is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A carbon-based multiphase coating film, characterized in that, The carbon matrix comprises, by volume percentage, 90% to 96% amorphous carbon phase, 3.1% to 8.8% graphite phase, and 1.2% to 1.5% diamond phase.

2. The carbon-based multiphase coating film according to claim 1, characterized in that, The amorphous carbon phase has an average grain size of 9.6 ~ 14.4 nm; the graphite phase has an average grain size of 8.7 ~ 17.2 nm; and the diamond phase has an average grain size of 9.9 ~ 13.0 nm.

3. The carbon-based multiphase coating film according to claim 1 or 2, characterized in that, It also includes a metallic conductive phase, wherein the metallic conductive phase is at least one of gold, silver, copper, platinum, or an alloy.

4. The carbon-based multiphase coating film according to claim 3, characterized in that, The metallic conductive phase is distributed in the carbon matrix in the form of particles, clusters, islands, discontinuous networks, or continuous networks.

5. A method for preparing a carbon-based multiphase coated thin film as described in any one of claims 1-4, characterized in that, Includes the following steps: S1. Clean, dry and pre-treat the substrate; S2. Provide a carbon source, wherein the carbon source is a graphite target; S3. In a vacuum deposition environment, a carbon-based multiphase coating film is formed on the surface of the substrate by deposition.

6. The method for preparing a carbon-based multiphase coated thin film according to claim 5, characterized in that, The graphite target power is 200W-500W, and the substrate temperature is 200℃-300℃.

7. The method for preparing a carbon-based multiphase coated thin film according to claim 5, characterized in that, A metal target is also provided in step S2; in step S3, the graphite target and the metal target are co-sputtered.

8. The method for preparing a carbon-based multiphase coated thin film according to claim 7, characterized in that, The metal target is a platinum target, and the power of the platinum target is 50 W - 100 W.

9. The method for preparing a carbon-based multiphase coated thin film according to claim 7, characterized in that, The substrate is one or more of copper, iron, gold, silver, FeCrNi alloy and their alloys.

10. The method for preparing a carbon-based multiphase coated thin film according to claim 7, characterized in that, The relative contents of graphite phase, diamond phase, and amorphous carbon phase in the carbon matrix are controlled by adjusting the substrate temperature and / or carbon source power; the metal content in the carbon matrix is ​​controlled by adjusting the substrate temperature and / or metal source power; and the sputtering thickness is adjusted by controlling the sputtering time. A carbon-based multiphase coating film with the desired total resistance and resistivity is obtained.

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