Graphene / copper composite film layer-by-layer stacked high-conductivity copper film and preparation method and application thereof

Abstract

The invention discloses a graphene / copper composite film layer-by-layer stacked high-conductivity copper film and a preparation method and application thereof.The preparation method comprises the following steps that S1, an insulating substrate is provided, a high-purity copper source serves as a material, and a copper film with the thickness ranging from 50 nm to 800 nm is deposited on the surface of the substrate through a physical vapor deposition technology; s2, growing a layer of graphene film with the coverage rate of 60%-90% on the surface of the copper film by adopting a chemical vapor deposition process to prepare a graphene / copper composite film; and S3, repeating the process of the steps S1 to S2 to obtain the product. According to the method, the conductivity of the metal copper film is improved by alternately and repeatedly depositing the copper and the defective graphene, so that the conductivity of the prepared copper film is greatly improved and even reaches 115.33% IACS (International Annealed Copper Standard), the fusing current is relatively high, the conductivity of the copper film is remarkably improved by the method, and the method is suitable for industrial production. The problem of low conductivity of copper materials in the field of integrated circuits can be effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of copper thin film materials, and in particular to a high-conductivity copper film formed by stacking graphene / copper composite films layer by layer, and a preparation method and application thereof. Background Art

[0002] With the development of large-scale integrated circuit technology, the requirements for material performance are increasing. Highly conductive copper thin films are of great significance in reducing energy consumption and improving circuit efficiency and stability. The introduction of highly conductive thin film materials helps reduce conductor losses, meet high-frequency and high-speed requirements, reduce RC delay, and improve circuit response speed and operating frequency. However, existing copper thin film preparation technologies suffer from low conductivity.

[0003] A Chinese invention patent (CN 119170344 A) discloses a technical solution for growing graphene on a copper foil surface and thermally depositing a copper film. This method involves repeatedly depositing copper and graphene on the surface of a macroscopic commercial copper foil of a certain thickness (typically greater than 25 microns), and then hot-pressing the deposited copper foil to produce a macroscopic bulk material for application. A Chinese invention patent (CN114959697 A) discloses a method for repeatedly depositing a copper film and graphene on a macroscopic copper foil (greater than 30 microns thick) using magnetron sputtering. The resulting copper foil also requires high-temperature hot pressing to become conductive.

[0004] In short, the existing copper thin film preparation technology requires high-temperature hot pressing of copper foil to make it conductive, and can only produce macroscopic blocks, so it cannot meet the future integrated circuit's demand for high conductivity of metallic copper. Summary of the Invention

[0005] The purpose of the present invention is to provide a highly conductive copper film stacked layer by layer with graphene / copper composite films, as well as a preparation method and application thereof, so as to solve the problem in the prior art that copper foil needs to be hot-pressed at high temperature to become conductive, and can only be prepared into macroscopic blocks, which cannot meet the demand for high conductivity of metallic copper in future integrated circuits.

[0006] In order to solve the above problems, the present invention adopts the following technical solutions:

[0007] According to a first aspect of the present invention, a method for preparing a highly conductive copper film comprising stacked layers of graphene / copper composite films is provided, comprising the following steps: S1, providing an insulating substrate, using a high-purity copper source as a material, and employing a physical vapor deposition process to deposit a copper film with a thickness of 50nm-800nm ​​on the surface of the substrate; S2, employing a chemical vapor deposition process to grow a layer of graphene film with a coverage of 60%-90% on the surface of the copper film to form a graphene / copper composite film; S3, repeating the process of step S1-step S2 to obtain a highly conductive copper film comprising stacked layers of graphene / copper composite films.

[0008] Preferably, the substrate in step S1 of the inventive method is a sapphire substrate or a silicon substrate.

[0009] In step S2 of the inventive method, the graphene film has a coverage of 60% to 90%. The coverage of the graphene film means that the graphene film only covers 60% to 90% of the surface area of ​​the copper film. The coverage is determined by the growth conditions, such as by controlling the growth time.

[0010] More preferably, the coverage of the graphene film is 70%-80%. Too high or too low will lead to lower electrical performance.

[0011] Preferably, in step S2, the thickness of the graphene film is 1-10 layers. It should be understood that the thickness of the graphene film refers to the thickness of the graphene film produced per cycle of growth. The layer here refers to one atomic layer.

[0012] Further preferably, in step S2, the thickness of the graphene film is 1-8 layers.

[0013] More preferably, in step S2, the thickness of the graphene film is 2-6 layers.

[0014] Preferably, in step S1, the thickness of the copper film is 50 nm-1000 nm.

[0015] Further preferably, in step S1, the thickness of the copper film is 100-800 nm.

[0016] More preferably, the thickness of the copper film is 200-500 nm.

[0017] The number of repeated cycles of repeatedly depositing copper and graphene in step S3 of the inventive method is 3-1000 times.

[0018] Further preferably, the number of repeated cycles of repeatedly depositing copper and graphene is 3-500 times.

[0019] Further preferably, the number of repeated cycles of copper and graphene deposition is 5 to 100. It should be understood that repeated cycle testing has an impact on the conductivity of the film, and too high or too low conductivity will lead to a decrease in electrical performance.

[0020] According to a preferred embodiment of the present invention, sapphire is selected as a copper thin film deposition substrate, which is placed in a thermal evaporation coating device to deposit a layer of high-purity and highly oriented copper thin film with a thickness of 300-800nm, and then a single layer of graphene with a coverage of 80-85% is deposited. 300-800nm ​​of copper and 80-85% of graphene are alternately deposited, and the cycle is repeated 5-10 times to obtain a highly conductive copper thin film composed of stacked layers of graphene / copper composite films.

[0021] According to a particularly preferred embodiment of the present invention, sapphire is selected as a copper thin film deposition substrate, which is placed in a thermal evaporation coating device to deposit a 300nm thick high-purity and highly oriented copper film. Then, a single layer of graphene with a coverage of 80% is deposited, and 300nm of copper and 80% of graphene are alternately deposited. The cycle is repeated 5 times to obtain a highly conductive copper film with a stack of graphene / copper composite films, whose electrical conductivity is 115.33% IACS.

[0022] According to another preferred embodiment of the present invention, sapphire is selected as a copper film deposition substrate, which is placed in a thermal evaporation coating device to deposit a 300nm thick high-purity and highly oriented copper film, and then a single layer of graphene with a coverage of 85% is deposited. 300nm of copper and 85% of graphene are alternately deposited, and the cycle is repeated 5 times to obtain a highly conductive copper film stacked layer by layer of graphene / copper composite films, whose electrical conductivity is 109% IACS.

[0023] According to a second aspect of the present invention, there is also provided a highly conductive copper film comprising stacked layers of graphene / copper composite films prepared by the above-mentioned preparation method.

[0024] According to a third aspect of the present invention, there is also provided an application of a highly conductive copper film formed by stacking layers of graphene / copper composite films prepared by the above preparation method in the field of integrated circuits.

[0025] It should be understood that the coverage of the graphene film is related to the graphene growth process, while the thickness of the copper film is related to the coating process, such as the coating time. Excessive or insufficient graphene film coverage, as well as excessive or thin copper film thickness, can negatively impact conductivity. Only the proper combination of these two values ​​can produce good electrical performance.

[0026] The key point of the present invention lies in pre-depositing a copper thin film on an insulating substrate via physical vapor deposition (PVD) as the base material. This method produces a relatively thin copper film, typically only a few hundred nanometers thick, which is primarily used in the integrated circuit field and in the microscopic realm. Existing techniques, on the other hand, primarily deposit copper onto a macroscopic foil and then hot-press it to produce a macroscopic bulk material, which is used in the macroscopic realm. Furthermore, the present invention utilizes an insulating substrate to deposit copper and graphene, resulting in a single-crystal copper film with superior electrical properties. The resulting material also contains a high graphene content.

[0027] It should also be understood that the present invention has prepared a kind of alternating stacking structure of graphene film and copper film, the thickness of copper film is relatively thin, the content of corresponding graphene is very high and graphene is continuously distributed. The application range of the material prepared by the present invention can be directly applied to the field of microelectronics, without the need for later hot pressing treatment. The traditional method is to deposit graphene on macroscopic commercial copper foil (copper foil with a thickness of tens of microns) and then repeatedly deposit copper and graphene, and then hot press to prepare macroscopic block material to make it have high conductivity, and is limited to application in the field of macroscopic electrical equipment, and is difficult to be applied to the field of microelectronics. In addition, while significantly improving the electrical conductivity of the material, the present invention also solves the problem that the prior art cannot significantly improve the content of graphene.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1) Significantly improved conductivity: The present invention produces a copper film with high conductivity by alternately cyclically depositing copper and graphene on an insulating substrate.

[0030] 2) Expanded application areas: The present invention produces a highly conductive copper thin film material with an overall thickness of only a few micrometers to a few millimeters, which can meet the future integrated circuit's demand for high conductivity of metallic copper and can be applied in the field of integrated circuits.

[0031] According to the method for preparing a highly conductive copper film comprising stacked layers of graphene / copper composite films provided by the present invention, a highly conductive copper film is prepared by alternately and cyclically depositing copper films and graphene films on the surface of an insulating substrate through physical vapor deposition and chemical vapor deposition. The electrical conductivity of the copper film obtained according to the method of the present invention is greatly improved, even as high as 115.33% IACS, and has a high fusing current. This method significantly improves the electrical conductivity of the copper film. The present invention can effectively solve the problem of low electrical conductivity of copper materials in the field of integrated circuits, improve the electrical conductivity of metallic copper films by alternately and repeatedly depositing copper and defective graphene, and is expected to be applied to the field of integrated circuit technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1This is a digital photo of the highly conductive copper film deposited cyclically in Example 1;

[0033] Figure 2 This is an optical microscopy image of the highly conductive copper film deposited cyclically in Example 1;

[0034] Figure 3 This is a Raman spectrum of the highly conductive copper film deposited cyclically in Example 1. DETAILED DESCRIPTION

[0035] The present invention will be further described below with reference to specific examples. It should be understood that the following examples are intended to illustrate the present invention only and are not intended to limit the scope of the present invention. Unless otherwise specified, the techniques used in the examples are conventional in the art, or according to the experimental methods recommended by the instrument and equipment manufacturers. The reagents and materials used in the examples are commercially available unless otherwise specified.

[0036] Example 1

[0037] Sapphire is selected as the copper film deposition substrate and placed in a thermal evaporation coating device to deposit 300nm thick copper. Finally, a layer of high-purity and highly oriented copper film is deposited on the sapphire. Then, a single layer of graphene with a coverage of 80% is deposited. 300nm copper and 80% graphene are deposited alternately. The cycle is repeated 5 times to obtain a wafer-level high-conductivity copper film material such as Figure 1 As shown. Figure 2 As shown in the figure, it can be seen that the surface of the high conductive copper film is flat. The conductivity of the sample is 115.33% IACS. The Raman spectrum of the cyclically deposited high conductive copper film prepared according to this embodiment is shown in the figure. Figure 3 shown.

[0038] Example 2

[0039] Sapphire was used as a substrate for copper film deposition and placed in a thermal evaporation coating apparatus to deposit 300nm of copper. Finally, a high-purity, highly oriented copper film was deposited on the sapphire. A single layer of graphene with an 85% coverage was then deposited. This alternating deposition of 300nm of copper and 85% graphene was repeated five times to produce a copper thin film. The resulting sample exhibited an electrical conductivity of 109% IACS. This differs from Example 1 in that the single layer of graphene with an 85% coverage yielded a 109% IACS conductivity.

[0040] Example 3

[0041] Sapphire was used as a substrate for copper film deposition and placed in a thermal evaporation coating apparatus to deposit 300nm of copper. Ultimately, a high-purity, highly oriented copper film was deposited on the sapphire. A single layer of graphene was then deposited to a 90% coverage. This alternating cycle of 300nm of copper and 90% graphene was repeated five times to produce a copper thin film. The resulting conductivity of this sample was 105.2% IACS. This differs from Example 1 in that the single layer of graphene had a 90% coverage, resulting in a 105.2% IACS conductivity.

[0042] Example 4

[0043] Sapphire was used as a substrate for copper film deposition and placed in a thermal evaporation coating apparatus to deposit 300nm of copper. This resulted in a high-purity, highly oriented copper film on the sapphire. A single layer of graphene was then deposited to a 60% coverage. This alternating cycle of 300nm of copper and 60% graphene was repeated five times to produce a copper thin film. The resulting sample exhibited a conductivity of 105.2% IACS. Compared to Example 1, the sample with 60% graphene coverage exhibited a conductivity of 105.2% IACS.

[0044] Example 5

[0045] Sapphire was used as the substrate for copper film deposition and placed in a thermal evaporation coating apparatus to deposit 800nm ​​of copper. Ultimately, a high-purity, highly oriented copper film was deposited on the sapphire. A single layer of graphene was then deposited to 80% coverage. This alternating cycle of 800nm ​​of copper and 80% graphene was repeated five times to produce a copper thin film. The resulting sample exhibited a conductivity of 103.2% IACS. This differs from Example 1 in that the copper film thickness was changed to 800nm, resulting in a sample with a conductivity of 103.2% IACS.

[0046] Example 6

[0047] Sapphire was used as a substrate for copper film deposition and placed in a thermal evaporation coating apparatus to deposit 50nm of copper. Ultimately, a high-purity, highly oriented copper film was deposited on the sapphire. A single layer of graphene was then deposited to 80% coverage. This alternating deposition of 50nm of copper and 80% graphene was repeated five times to produce a copper thin film. The resulting sample exhibited a conductivity of 103.5% IACS. Compared to Example 1, the copper film thickness was changed to 50nm, resulting in a sample with a conductivity of 103.5% IACS.

[0048] Comparative Example 1

[0049] Sapphire was used as a substrate for copper film deposition and placed in a thermal evaporation coating apparatus to deposit 300nm of copper. This resulted in a high-purity, highly oriented copper film on the sapphire. A single layer of graphene was then deposited to a 91% coverage. This alternating cycle of 300nm of copper and 91% graphene was repeated five times to produce a copper thin film. The resulting conductivity of this sample was 102.2% IACS. This differs from Example 1 in that the single layer of graphene had a 91% coverage, resulting in a 102.2% IACS conductivity.

[0050] Comparative Example 2

[0051] Sapphire was used as a substrate for copper film deposition and placed in a thermal evaporation coating apparatus to deposit 300nm of copper. This resulted in a high-purity, highly oriented copper film on the sapphire. A single layer of graphene was then deposited to a 58% coverage. This alternating cycle of 300nm of copper and 58% graphene was repeated five times to produce a copper thin film. The resulting conductivity of this sample was 103.8 IACS. Compared to Example 1, the conductivity of the sample obtained with a single layer of graphene at 58% coverage was 102.8% IACS.

[0052] Comparative Example 3

[0053] Sapphire was used as the substrate for copper film deposition and placed in a thermal evaporation coating apparatus to deposit 900nm of copper. Ultimately, a high-purity, highly oriented copper film was deposited on the sapphire. Next, a single layer of graphene was deposited to 80% coverage. This cycle was repeated five times, alternating between 800nm ​​of copper and 80% graphene coverage, to produce a copper thin film. The resulting sample exhibited a conductivity of 101.2% IACS. This differs from Example 1 in that the copper film thickness was changed to 900nm, resulting in a 101.2% IACS conductivity.

[0054] Comparative Example 4

[0055] Sapphire was used as the substrate for copper film deposition and placed in a thermal evaporation coating apparatus to deposit 40nm of copper. Ultimately, a high-purity, highly oriented copper film was deposited on the sapphire. Next, a single layer of graphene was deposited to 80% coverage. This cycle was then repeated five times, alternating between 50nm of copper and 80% graphene coverage, to produce a copper thin film. The resulting sample exhibited a conductivity of 101.5% IACS. Compared to Example 1, the copper film thickness was changed to 40nm, resulting in a 101.5% IACS conductivity.

[0056] Comparative Example 5

[0057] A 30-micron-thick commercial copper foil was placed in a thermal evaporation process to deposit a single layer of graphene with an 80% coverage, followed by a 300-nm-thick copper layer. This cycle was repeated five times, resulting in a sample with a conductivity of 100.2% IACS. This differs from Example 1 in that the first copper layer was a commercial macro copper foil.

[0058] Table 1 Conductivity measurement results of Examples 1-6 and Comparative Examples 1-5 Case Conductivity (%IACS) Example 1 115.33 Example 2 109 Example 3 105.2 Example 4 105.2 Example 5 103.2 Example 6 103.5 Comparative Example 1 102.2 Comparative Example 2 102.8 Comparative Example 3 101.2 Comparative Example 4 101.5 Comparative Example 5 100.2％

[0059] The conductivity measurements of the copper thin film materials prepared in Examples 1-6 and Comparative Examples 1-5 are shown in Table 1. As can be seen from Table 1, the copper thin films obtained according to the present invention generally have conductivity levels ≥ 103.2% IACS, some as high as 115.33% IACS, and exhibit high fusing currents, demonstrating that this method significantly improves the conductivity of the copper thin films. The copper thin film materials prepared in Comparative Examples 1-5 generally have lower conductivity levels.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Various modifications are possible. Any simple, equivalent changes and modifications made in accordance with the claims and description of the present invention are within the scope of protection of the patent claims. Anything not fully described in this invention is conventional technology.

Claims

1. A method for preparing a highly conductive copper film stacked layer by layer of graphene / copper composite films, characterized in that: The steps include: S1, providing an insulating substrate, using a high-purity copper source as a material, and depositing a copper thin film with a thickness of 50nm-800nm ​​on the surface of the insulating substrate by a physical vapor deposition process; S2, growing a graphene film with a coverage of 60% to 90% on the surface of the copper film using a chemical vapor deposition process to form a graphene / copper composite film; S3, repeating the process of step S1-step S2 to obtain a highly conductive copper film stacked layer by layer of graphene / copper composite films.

2. The preparation method according to claim 1, characterized in that In step S1, the insulating substrate is a sapphire substrate or a silicon substrate.

3. The preparation method according to claim 1, characterized in that In step S1, the thickness of the copper film is 300-800 nm.

4. The preparation method according to claim 1, characterized in that In step S2, the graphene film has a coverage of 80%-85%.

5. The preparation method according to claim 1, characterized in that The number of repeated cycles of depositing copper and graphene in step S3 is 3-100 times.

6. The preparation method according to claim 1, characterized in that In step S2, the number of layers of the graphene film is 1-10.

7. The preparation method according to claim 1, characterized in that The operation process of preparing the graphene copper composite film from step S1 to step S3 is carried out in the same chamber.

8. The preparation method according to claim 1, characterized in that Sapphire is selected as the copper film deposition substrate and placed in a thermal evaporation coating device to deposit a layer of high-purity and highly oriented copper film with a thickness of 300-800nm. Then, a single layer of graphene with a coverage of 80-85% is deposited. 300-800nm ​​of copper and graphene with a coverage of 80-85% are alternately deposited. The cycle is repeated 5-10 times to obtain a highly conductive copper film with stacked layers of graphene / copper composite films.

9. A highly conductive copper film comprising stacked graphene / copper composite films prepared according to the preparation method of any one of claims 1 to 8.

10. Application of a highly conductive copper film comprising stacked layers of graphene / copper composite films prepared by the preparation method according to any one of claims 1 to 8 in the field of integrated circuits.

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