A copper-based alloy single crystal wafer preparation method based on surface energy regulation

Abstract

The application discloses a copper-based alloy single crystal wafer preparation method based on surface energy regulation. The method comprises the following steps: S1, depositing a high surface energy metal film on a copper-plated surface in a Cu(111) / sapphire single crystal wafer, wherein the high surface energy metal is a metal with a surface energy greater than that of copper; S2, re-depositing a copper film on the surface of the high surface energy metal film in the high surface energy metal / Cu(111) / sapphire wafer obtained in the step S1; and S3, placing the copper / high surface energy metal / Cu(111) / sapphire wafer obtained in the step S2 in a chemical vapor deposition reaction chamber and performing annealing recrystallization. The Cu(111) single crystal wafer with a relatively mature process is used as a template, so that the in-plane twin problem existing in the direct single crystallization process of the existing copper-based alloy wafer can be effectively solved. Meanwhile, through the surface energy regulation strategy, the solid-state dewetting phenomenon of the high surface energy metal layer can be successfully inhibited, so that the controllable preparation of the ultra-flat copper-based alloy single crystal metal wafer can be realized.

Description

Technical Field

[0001] This invention belongs to the field of materials preparation, specifically relating to a method for preparing copper-based alloy single-crystal wafers. Background Technology

[0002] Graphene, with its ultra-high carrier mobility, unique optical response, excellent mechanical strength, and good chemical stability, holds immense application potential in the field of electronic information. To realize the construction of high-performance electronic and optoelectronic devices, graphene requires low defect density and high property uniformity. Therefore, graphene single-crystal wafers prepared by chemical vapor deposition (CVD) are the preferred material. Compared to other CVD graphene thin film materials, graphene single-crystal wafers possess extremely low grain boundary density, an ultra-flat surface structure, and a material morphology compatible with semiconductor integration processes, thus being regarded as a key supporting material for the development of next-generation carbon-based integrated circuits.

[0003] For the epitaxial growth of graphene single-crystal wafers, the first step is to design a single-crystal catalytic substrate. Currently, Cu(111) / sapphire single-crystal wafers prepared by magnetron sputtering and annealing recrystallization are the mainstream substrates for graphene single-crystal wafer preparation. This is mainly because Cu(111) and graphene have good lattice and symmetry matching, which can induce consistent growth of graphene domain orientation and ultimately seamless splicing into a single-crystal film. However, due to the catalytic activity and carbon solubility of the copper film itself, the growth of graphene on its surface usually faces bottlenecks such as slow growth rate, low efficiency, and poor layer scalability. In contrast, copper-based alloy single-crystal wafer substrates constructed with Cu(111) as the main component, due to the tunability of the catalytic activity of its components and the carbon solubility, can improve the growth rate and layer controllability while ensuring the quality of graphene epitaxial growth. Therefore, they have greater potential for achieving precise synthesis and large-scale preparation of graphene wafer materials for specific applications.

[0004] For the preparation of copper-based alloy single-crystal wafer substrates, Cu(111) single-crystal thin films are currently mainly used as epitaxial templates. Other metal layers are first deposited on the surface using magnetron sputtering, followed by high-temperature annealing and recrystallization to achieve alloying and single-crystalization. However, alloying elements with suitable catalytic activity and carbon solubility, such as Ni, Pt, and Pd, have higher surface energies than copper. Therefore, during the high-temperature annealing stage, the introduced metal layers, due to the dense and slow diffusion of the Cu(111) lattice, tend to undergo lateral solid-state dewetting to reduce the overall surface energy of the film. This results in a large number of pore structures on the surface of the final single-crystal substrate, significantly affecting the surface flatness of the substrate and the subsequent epitaxial growth quality of graphene single crystals. It is worth mentioning that although some literature reports the simultaneous deposition of copper and other metal components on the surface of a sapphire substrate via co-sputtering, followed by high-temperature annealing to prepare copper-based alloy single-crystal wafers, the single-crystalization evolution of the alloy thin film in the above process is more complex and faces serious in-plane twinning problems, requiring further improvement in the single-crystal size and yield of the final alloy substrate. Therefore, in order to expand the selection of growth substrates for graphene single crystal wafers and further promote their practical application in next-generation carbon-based electronic and optoelectronic chips, it is urgent to develop a universal construction method for large-size, ultra-flat copper-based alloy single crystal wafers. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing copper-based alloy single-crystal wafers based on surface energy regulation. This method involves first depositing other metal layers with high surface energy on the surface of a Cu(111) single-crystal wafer, and then depositing a copper layer with low surface energy. In this way, the lateral spreading of the outermost copper layer is used to suppress the solid dehumidification process of the other metal layers below during the high-temperature annealing stage, and finally, a large-size, non-porous, and ultra-flat copper-based alloy single-crystal wafer can be obtained.

[0006] In a first aspect, the present invention provides a method for preparing copper-based alloy single-crystal wafers based on surface energy modulation, comprising the following steps: S1. A high surface energy metal film is deposited on the copper-plated surface of a Cu(111) / sapphire single crystal wafer, wherein the surface energy metal is a metal with a surface energy greater than that of copper. S2. A copper film is redeposited on the surface of the high surface energy metal film in the high surface energy metal / Cu(111) / sapphire wafer obtained in step S1. S3. Place the copper / high surface energy metal / Cu(111) / sapphire wafer obtained in step S2 into a chemical vapor deposition reaction chamber for annealing and recrystallization.

[0007] Based on the above technical solutions, such as Figure 1As shown, compared with the traditional method, the present invention first deposits other metal layers with high surface energy on the surface of Cu(111) single crystal wafer during the sputtering process, and then deposits a copper layer with low surface energy. The lateral spreading of the lower surface energy copper layer suppresses the dehumidification process of the other metal layers below, and finally obtains a copper-based alloy single crystal wafer with no pore structure and ultra-flat surface energy.

[0008] In the above-mentioned method for preparing copper-based alloy single-crystal wafers based on surface energy regulation, the sapphire single-crystal wafer is a sapphire single-crystal wafer with a c-plane orientation. The lateral dimension of the sapphire single crystal wafer is 2 to 6 inches, preferably 4 inches; The thickness of the sapphire wafer is 400–1200 μm, preferably 650 μm; In the Cu(111) / sapphire single crystal wafer, the thickness of the Cu(111) film is 400–2000 nm, preferably 500 nm.

[0009] In the above-mentioned method for preparing copper-based alloy single-crystal wafers based on surface energy regulation, preferably, the metal with a surface energy greater than that of copper includes any one of Ni, Pt, Pd, and Co.

[0010] In the above-mentioned method for preparing copper-based alloy single-crystal wafers based on surface energy regulation, the thickness of the high surface energy metal film is 5–500 nm, preferably 60 nm.

[0011] In the above-mentioned method for preparing copper-based alloy single-crystal wafers based on surface energy regulation, the step of depositing a high surface energy metal film is performed by magnetron sputtering with a deposition power of 50–200 W, preferably 150 W; the deposition temperature is room temperature (20–25 °C).

[0012] In the above-mentioned method for preparing copper-based alloy single-crystal wafers based on surface energy regulation, the thickness of the copper film is 20–1000 nm, preferably 40 nm.

[0013] In the above-mentioned method for preparing copper-based alloy single-crystal wafers based on surface energy regulation, the copper film deposition step is performed by magnetron sputtering with a deposition power of 50–200 W, preferably 150 W; the deposition temperature is room temperature (20–25 °C).

[0014] In the above-mentioned method for preparing copper-based alloy single-crystal wafers based on surface energy regulation, the annealing and recrystallization conditions are as follows: the annealing temperature is 700–1100 °C, preferably 1000 °C; the annealing time is 30–180 min, preferably 30 min; the annealing atmosphere is argon and hydrogen, with gas flow rates of 10–1000 sccm for hydrogen and 100–3000 sccm for argon, preferably 500 sccm for hydrogen and 500 sccm for argon; and the annealing system pressure is atmospheric pressure (101 kPa).

[0015] Secondly, the present invention provides a copper-based alloy single-crystal wafer based on surface energy modulation obtained by any of the above-described preparation methods. The copper-based alloy single-crystal wafer has a large size, a smooth surface, and no obvious dehumidification pores.

[0016] Thirdly, the present invention provides the application of the surface energy-tunable copper-based alloy single-crystal wafer in the growth of two-dimensional materials on a substrate, such as single-crystal graphene wafer.

[0017] The present invention has the following beneficial effects: This method exhibits good reproducibility and scalability, enabling the controllable fabrication of 2- to 6-inch single-crystal wafers of different compositions, including CuNi(111), CuPt(111), and CuPd(111). This method is significant for clarifying the single-crystallization evolution mechanism of copper-based alloy thin films and promoting the mass production of single-crystal alloy wafers. Furthermore, this method can provide a rich selection of epitaxial substrates for the controllable growth of wafer-level two-dimensional nanomaterials, such as graphene, potentially further promoting the practical application of two-dimensional materials in novel electronic and optoelectronic devices. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the preparation of copper-based alloy single-crystal wafers based on surface energy modulation according to the present invention.

[0019] Figure 2 This is the evaluation result of the number of dehumidification vias on the four-inch CuNi(111) wafer in Example 1.

[0020] Figure 3 This is the evaluation result of the number of dehumidification vias on the four-inch CuPt(111) wafer in Example 2.

[0021] Figure 4 This is the evaluation result of the number of dehumidification vias on the four-inch CuPd(111) wafer in Example 3.

[0022] Figure 5 The images in the middle, from left to right, show the single crystallinity evaluation results of four-inch CuNi, CuPt, and CuPd wafers from Examples 1-3.

[0023] Figure 6This is an evaluation result of the number of dehumidification holes in a four-inch CuNi(111) wafer prepared without surface energy modulation in Comparative Example 1.

[0024] Figure 7 This is an evaluation result of the number of dehumidification holes in the four-inch CuPt(111) wafer prepared in Comparative Example 2 without surface energy modulation.

[0025] Figure 8 This is an evaluation result of the number of dehumidification holes in the four-inch CuPd(111) wafer prepared in Comparative Example 3 without surface energy modulation.

[0026] Figure 9 The results show the morphology of the dehumidification holes on the four-inch CuNi(111) wafer of Comparative Example 1. The morphology of the dehumidification holes in other comparative examples is similar to that of Comparative Example 1. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.

[0028] Unless otherwise specified, the methods used in the following embodiments are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following embodiments are commercially available.

[0029] Example 1: Fabrication of a four-inch CuNi(111) single crystal wafer according to Figure 1 The surface energy modulation strategy shown is used to prepare a four-inch CuNi(111) single crystal wafer. The specific steps are as follows: Step 1: Deposit a 60 nm Ni metal layer on the surface of a 4-inch Cu(111) / sapphire single crystal wafer (c-plane orientation, sapphire wafer thickness of 650 μm, Cu(111) film thickness of 500 nm). The specific operation is as follows: Fix the Cu(111) / sapphire single crystal wafer with the copper plated side facing up on the tray and transfer it to the process chamber of the magnetron sputtering equipment. Sputter the Ni target onto the Cu(111) wafer at a sputtering power of 150 W and a sputtering temperature of room temperature to form a 60 nm Ni metal film. Step 2: Deposit a 40 nm Cu metal layer on the surface of the Ni metal layer deposited in Step 1. The specific operation is as follows: Sputter the Cu target onto the surface of the Ni metal layer with a sputtering power of 150 W and a sputtering temperature of room temperature to form a 40 nm Cu metal thin film. Step 3: Place the alloy film obtained by sputtering in Step 2 into the CVD reaction chamber for high-temperature annealing and recrystallization treatment. The annealing temperature is 1000 ℃, the annealing time is 30 min, the annealing atmosphere is a hydrogen-argon mixture, the hydrogen flow rate is 500 sccm, the argon flow rate is 500 sccm, and the annealing pressure is atmospheric pressure (101 kPa). After annealing, the original atmosphere is cooled to room temperature, and a sample is taken to obtain a CuNi(111) single crystal wafer with a smooth surface.

[0030] Example 2: Fabrication of a four-inch CuPt(111) single crystal wafer Other experimental conditions were the same as in Example 1, except that the deposited 60 nm Ni metal layer was replaced with a 60 nm Pt metal layer.

[0031] Example 3: Fabrication of a four-inch CuPd(111) single crystal wafer Other experimental conditions were the same as in Example 1, except that the deposited 60 nm Ni metal layer was replaced with a 60 nm Pd metal layer.

[0032] Comparative Example 1 Similar to steps one and three in Example 1, a 60 nm Ni metal layer was directly deposited on the surface of a four-inch Cu(111) / sapphire single crystal wafer, and the sputtered CuNi metal film was placed in the CVD reaction chamber for high-temperature annealing and recrystallization. The experimental conditions were the same as in Example 1, except that the deposition of the Cu metal layer (step two) was omitted.

[0033] Comparative Example 2 Similar to steps one and three in Example 2, a 60 nm Pt metal layer was directly deposited on the surface of a four-inch Cu(111) / sapphire single crystal wafer, and the sputtered CuPt metal film was placed in the CVD reaction chamber for high-temperature annealing and recrystallization. The experimental conditions were the same as in Example 2, except that the deposition of the Cu metal layer (step two) was omitted.

[0034] Comparative Example 3 Similar to steps one and three in Example 3, a 60 nm Pd metal layer was directly deposited on the surface of a four-inch Cu(111) / sapphire single crystal wafer, and the sputtered CuPd metal film was placed in the CVD reaction chamber for high-temperature annealing and recrystallization. The experimental conditions were the same as in Example 1, except that the deposition of the Cu metal layer (step two) was omitted.

[0035] The number of dehumidification holes and the single crystal properties of the copper-based alloy single crystal wafers prepared in Examples 1-3 and Comparative Examples 1-3 were evaluated.

[0036] Figures 2-4This document presents the progressively magnified characterization and identification results of the surface morphology of the copper-based single-crystal wafers prepared in Examples 1-3, achieved through optical imaging, image stitching, and automated recognition and analysis using a wafer-level automated optical characterization platform. It can be seen that the copper-based alloy wafers prepared using the surface energy modulation strategy have smooth surfaces, no grain boundaries, and no obvious dehumidification pores.

[0037] Figure 5 The following are the characterization results of the single crystallinity of the four-inch copper-based alloy wafers in Examples 1-3, respectively. Characterization by electron backscatter diffraction (EBSD) shows that the prepared four-inch copper-based alloy single crystal wafers have only one orientation both in-plane and out-of-plane, and no twins are formed.

[0038] Figures 6-8 This is a wafer-level optical evaluation result of the number of dehumidification holes on the four-inch copper-based alloy single-crystal wafers prepared without surface energy modulation, as shown in Examples 1-3. It can be seen that the four-inch copper-based alloy single-crystal wafers prepared without surface energy modulation have a very large number of dehumidification holes on their surface.

[0039] Figure 9 The morphology characterization results of the dehumidification holes on the CuNi(111) single crystal wafer in Comparative Example 1 are shown. Atomic force microscopy (AFM) characterization results show that the obtained dehumidification holes have a regular hexagonal structure. The metal film at the location of the dehumidification hole is completely dehumidified, directly exposing the sapphire substrate, proving that the presence of the dehumidification holes disrupts the continuity and surface flatness of the alloy film.

[0040] The present invention has been described in detail above. Those skilled in the art will recognize that the invention can be practiced in a wide range of ways with equivalent parameters, concentrations, and conditions without departing from its spirit and scope. While specific embodiments have been provided, it should be understood that further modifications can be made to the invention. In summary, according to the principles of the invention, this application is intended to include any changes, uses, or improvements to the invention, including modifications made using conventional techniques known in the art that depart from the scope disclosed herein.

Claims

1. A method for preparing copper-based alloy single-crystal wafers based on surface energy modulation, characterized in that, Includes the following steps: S1. A high surface energy metal film is deposited on the copper-plated surface of a Cu(111) / sapphire single crystal wafer, wherein the high surface energy metal is a metal with a surface energy greater than that of copper. S2. A copper film is re-deposited on the surface of the high surface energy metal film in the high surface energy metal / Cu(111) / sapphire wafer obtained in step S1. S3. Place the copper / high surface energy metal / Cu(111) / sapphire wafer obtained in step S2 into a chemical vapor deposition reaction chamber for annealing and recrystallization.

2. The method for preparing copper-based alloy single-crystal wafers based on surface energy modulation according to claim 1, characterized in that: The sapphire single crystal wafer is a sapphire single crystal wafer with the crystal plane orientation of the c-plane; The lateral dimensions of the sapphire single crystal wafer are 2 to 6 inches; The thickness of the sapphire wafer is 400–1200 μm; In the Cu(111) / sapphire single crystal wafer, the thickness of the Cu(111) film is 400–2000 nm.

3. The method for preparing copper-based alloy single-crystal wafers based on surface energy modulation according to any one of claims 1-2, characterized in that: The high surface energy metal includes any one of Ni, Pt, Pd, and Co.

4. The method for preparing copper-based alloy single-crystal wafers based on surface energy modulation according to any one of claims 1-3, characterized in that: The thickness of the high surface energy metal film is 5–500 nm.

5. The method for preparing copper-based alloy single-crystal wafers based on surface energy modulation according to any one of claims 1-4, characterized in that: The high surface energy metal film deposition step employs magnetron sputtering with a deposition power of 50–200 W and a deposition temperature of room temperature.

6. The method for preparing copper-based alloy single-crystal wafers based on surface energy modulation according to any one of claims 1-5, characterized in that: The thickness of the copper film is 20–1000 nm.

7. The method for preparing copper-based alloy single-crystal wafers based on surface energy modulation according to any one of claims 1-6, characterized in that: The copper film deposition step employs magnetron sputtering with a deposition power of 50–200 W and a deposition temperature of room temperature.

8. The method for preparing copper-based alloy single-crystal wafers based on surface energy modulation according to any one of claims 1-7, characterized in that: The annealing and recrystallization conditions are as follows: annealing temperature is 700–1100 °C, annealing time is 30–180 min; the annealing atmosphere is argon and hydrogen, with a gas flow rate of 10–1000 sccm for hydrogen and 100–3000 sccm for argon; and the annealing system pressure is atmospheric pressure.

9. The copper-based alloy single-crystal wafer based on surface energy modulation obtained by the preparation method of any one of claims 1-8.

10. The application of the surface energy-tunable copper-based alloy single-crystal wafer of claim 9 in the growth of two-dimensional materials on a substrate.

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