Heteroepitaxial monocrystal diamond based on pre-laid nucleation carbon source and preparation method thereof

Abstract

The invention discloses a heteroepitaxial monocrystal diamond based on a pre-laid nucleation carbon source and a preparation method of the heteroepitaxial monocrystal diamond. The method comprises the following steps: S10, obtaining a heterogeneous substrate; s20, forming a nucleation carbon source layer on one side of the heterogeneous substrate; s30, forming an iridium metal layer on one side, far away from the heterogeneous substrate, of the nucleation carbon source layer; s40, introducing a carbon-free precursor process gas by adopting an MPCVD (Micro Plasma Chemical Vapor Deposition) process; forming a diamond nucleating layer on one side, far away from the heterogeneous substrate, of the iridium metal layer through bias processing; and S50, introducing a carbon-containing precursor process gas by adopting an MPCVD process, and growing on the diamond nucleating layer to obtain the single crystal diamond layer. According to the method, the nucleation carbon source layer is pre-laid under the iridium metal layer, so that carbon in the nucleation carbon source layer under the iridium metal is directly separated out in the nucleation process to form the diamond nucleation layer, damage to the iridium metal on the heterogeneous substrate in the nucleation process is reduced, and the quality of the epitaxial growth diamond layer is improved.

Description

Technical Field

[0001] This invention belongs to the field of diamond epitaxial growth technology, specifically relating to a heteroepitaxial single-crystal diamond based on a pre-laid nucleation carbon source and its preparation method. Background Technology

[0002] Diamond, as an ultrawide bandgap semiconductor material, possesses outstanding physical and chemical properties, including an extremely wide bandgap (~5.5 eV), extremely high thermal conductivity (>2200 W / m·K), and high carrier mobility (electrons ~4500 cm⁻¹). 2 / V·s, Hole ~3800 cm 2 Diamond possesses a high breakdown field strength (>10 MV / cm) and an extremely high voltage-to-saturation field (V·s). These properties make diamond an ideal material for fabricating high-voltage, high-frequency, and high-power semiconductor devices, as well as electronic devices resistant to extreme environments, with broad application prospects in strategic fields such as 5G / 6G communications, new energy, and space science. Compared to traditional silicon-based semiconductors, diamond devices can operate stably at higher temperatures, higher voltages, and harsher environments, and are considered a key player in material innovation in the "post-Moore's Law era."

[0003] Despite the numerous superior properties of diamond, its application in the semiconductor field has long been limited by the size of single-crystal substrates. Natural diamond is small and expensive, while artificial single-crystal diamonds prepared by the traditional high-pressure, high-temperature (HPHT) method are typically limited to below centimeter-sized wafers, failing to meet the basic wafer size requirements of the modern semiconductor industry. Although chemical vapor deposition (CVD) technology has provided a new avenue for diamond growth, homoepitaxial growth is still limited by seed crystal size, making it difficult to prepare large-area single-crystal diamonds. Therefore, developing a technology that enables the direct epitaxial growth of large-size single-crystal diamonds on heterogeneous substrates has become crucial for promoting the application of diamond in semiconductors.

[0004] In the study of heteroepitaxial growth of single-crystal diamond, iridium (Ir) has been proven to be the optimal nucleation layer material due to its unique carbon atom solubility characteristics and surface energy features. Currently, heteroepitaxial growth of single-crystal diamond is basically achieved by growing high-quality, single-crystal-oriented iridium metal on a heterogeneous substrate, and then further realizing the heteroepitaxial growth of large-size single-crystal diamonds on the iridium metal layer.

[0005] The heteroepitaxial growth of single-crystal diamond generally involves three steps: first, depositing iridium metal; second, forming diamond nuclei with a single crystal orientation on the iridium metal; and finally, merging the grown diamonds to prepare large-size single-crystal diamonds. However, in traditional heteroepitaxial processes, the carbon element required for diamond nucleation typically comes from carbon-containing groups in the growth environment. These carbon-containing groups first penetrate the iridium metal layer and then precipitate to form diamond nuclei. But as long as carbon-containing groups are present, not only nucleation but also diamond growth will occur on the heterostructure surface. This growth may occur on the newly formed diamond nuclei or directly on the iridium metal, resulting in amorphous diamond particles. Because the process conditions for nucleation differ significantly from those for subsequent growth, the diamonds grown in this process are essentially unnecessary and negatively impact the subsequent growth process. These diamonds lack a uniform crystal orientation, which significantly affects the later diamond growth process, resulting in single-crystal diamonds obtained through heteroepitaxial growth that fall far short of usable quality.

[0006] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0007] To address the aforementioned problems in the prior art, this invention provides a heteroepitaxial single-crystal diamond based on a pre-laid nucleation carbon source and its preparation method. The technical problem to be solved by this invention is achieved through the following technical solution: In a first aspect, the present invention provides a method for preparing heteroepitaxial single-crystal diamond based on a pre-laid nucleated carbon source, comprising the following steps: S10, Obtain the heterogeneous substrate; S20. A nucleation carbon source layer is formed on one side of the heterogeneous substrate; S30. An iridium metal layer is formed on the side of the nucleation carbon source layer away from the heterogeneous substrate; S40. A microwave plasma chemical vapor deposition process is used to introduce a carbon-free precursor process gas; and a bias voltage is applied to the side of the heterogeneous substrate away from the nucleation carbon source layer and the side of the iridium metal layer away from the nucleation carbon source layer, so that the carbon source of the nucleation carbon source layer is precipitated from the iridium metal layer, and a diamond nucleation layer is formed on the side of the iridium metal layer away from the heterogeneous substrate. S50. A single-crystal diamond layer is grown on the diamond nucleation layer by introducing a carbon-containing precursor process gas using microwave plasma chemical vapor deposition.

[0008] In one embodiment of the present invention, step S20, forming the nucleation carbon source layer includes using a chemical vapor deposition process or a polymer-assisted transfer process.

[0009] In one embodiment of the present invention, the material of the nucleation carbon source layer is graphite or graphene.

[0010] In one embodiment of the present invention, step S40 includes: The sample obtained in step S30 is defined as the first sample; the first sample is placed in a microwave plasma chemical vapor deposition apparatus; wherein, the heterogeneous substrate is close to the first metal electrode plate, and the iridium metal layer is close to the second metal electrode plate; The cavity pressure of the microwave plasma chemical vapor deposition equipment is evacuated to less than or equal to 0.001 mbar; Hydrogen gas (H2) is introduced into the microwave plasma chemical vapor deposition equipment at a flow rate of 100–800 sccm; when the cavity pressure of the microwave plasma chemical vapor deposition equipment reaches 10–25 mbar, the microwave source is turned on. When the microwave plasma chemical vapor deposition equipment reaches the preset parameters, a negative voltage is applied to the first metal electrode plate and a positive voltage is applied to the second metal electrode plate for bias treatment; the bias treatment time is 5 to 120 minutes.

[0011] In one embodiment of the present invention, the preset parameters are: the cavity gas pressure of the microwave plasma chemical vapor deposition equipment is 20-100 mbar, the microwave power is 600-2500 W, and the surface temperature of the side of the first sample away from the heterogeneous substrate is 400-600°C.

[0012] In one embodiment of the present invention, step S50 includes: The sample processed in step S40 is defined as the second sample; the second sample is placed in a microwave plasma chemical vapor deposition apparatus. The cavity gas pressure of the microwave plasma chemical vapor deposition equipment is adjusted to 120-200 mbar, the microwave power is 3000-5000 W, and the surface temperature of the side of the second sample away from the heterogeneous substrate is 800-1000 °C. Methane (CH4), oxygen (O2), and nitrogen (N2) were introduced into a microwave plasma chemical vapor deposition (IPD) apparatus. The flow rates of methane (CH4) were 7–72 sccm, oxygen (O2) were 0.5–20 sccm, and nitrogen (N2) were 0.001–4 sccm. Single-crystal diamond was grown for 48–168 h.

[0013] In one embodiment of the present invention, the thickness of the nucleation carbon source layer is 5-50 nm; the thickness of the iridium metal layer is 15-50 nm. The thickness of the single-crystal diamond layer is 0.5–3 mm.

[0014] In one embodiment of the present invention, the heterogeneous substrate is a magnesium oxide substrate, a sapphire substrate, a strontium titanate substrate, or a single-crystal silicon-based yttrium oxide-stabilized zirconium oxide film composite substrate.

[0015] In one embodiment of the present invention, the formation of the iridium metal layer is achieved by magnetron sputtering, electron beam evaporation, or pulsed laser deposition.

[0016] Secondly, the present invention provides a heteroepitaxial single-crystal diamond based on a pre-laid nucleated carbon source, which is obtained by the above-described preparation method.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The heteroepitaxial single-crystal diamond preparation method based on pre-laid nucleation carbon sources provided by this invention simplifies the traditional heteroepitaxial growth process of injecting carbon-containing groups into the iridium metal and then precipitating them by pre-laying a nucleation carbon source layer under an iridium metal layer. Instead, it directly precipitates the carbon source from the nucleation carbon source layer under the iridium metal layer to form the diamond nucleation layer. This significantly reduces the damage to the iridium metal on the heteroepitaxial substrate during nucleation, thereby optimizing the subsequent heteroepitaxial growth process.

[0018] 2. In the method provided by this invention, since the carbon source is transformed from the carbon-containing groups in the microwave plasma chemical vapor deposition process atmosphere to the nucleation carbon source layer located under the iridium metal layer, a carbon-free precursor process gas is introduced during the nucleation process of heteroepitaxial growth. Thus, unnecessary diamond particles do not appear during nucleation, improving the crystal orientation consistency of the diamond nuclei in the diamond nucleation layer, making it easier for diamond nuclei to merge during subsequent growth, and significantly optimizing the quality of the single-crystal diamond prepared by heteroepitaxial growth.

[0019] 3. In the solution provided by the present invention, since the carbon source during the nucleation process is provided by a carbon-free precursor process gas, the nucleation and growth processes in diamond heteroepitaxialization can be distinguished by whether or not a carbon-containing precursor process gas is introduced. This is more conducive to the research and optimization of subsequent diamond heteroepitaxialization processes, and more beneficial to promoting industrial upgrading, process standardization and scaling, and further laying the foundation for the application of heteroepitaxial single crystal diamond.

[0020] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a heteroepitaxial single-crystal diamond preparation method based on a pre-laid nucleated carbon source provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure prepared in step S10 of this embodiment of the invention; Figure 3This is a schematic diagram of the structure prepared in step S20 of this embodiment of the invention; Figure 4 This is a schematic diagram of the structure prepared in step S30 of this embodiment of the invention; Figure 5 This is a schematic diagram of step S40 of the embodiment of the present invention, which involves the diamond nucleation process. Figure 6 This is a schematic diagram of the diamond growth process in step S50 of an embodiment of the present invention; Figure 7 This is a schematic diagram of a structure with a single-crystal diamond layer provided in an embodiment of the present invention.

[0022] Explanation of reference numerals in the attached figures: 1-Heterogeneous substrate; 2-Nucleation carbon source layer; 3-Iridium metal layer; 41-First metal electrode plate; 42-Second metal electrode plate; 5-Carbon-free precursor process gas; 6-Diamond nucleation layer; 7-Carbon-containing precursor process gas; 8-Single crystal diamond layer. Detailed Implementation

[0023] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the following, in conjunction with the accompanying drawings and specific embodiments, provides a detailed description of a heteroepitaxial single-crystal diamond based on a pre-laid nucleated carbon source and its preparation method.

[0024] The foregoing and other technical contents, features, and effects of the present invention will be clearly presented in the following detailed description of specific embodiments in conjunction with the accompanying drawings. Through the description of the specific embodiments, a more in-depth and concrete understanding can be gained of the technical means and effects adopted by the present invention to achieve its intended purpose. However, the accompanying drawings are for reference and illustration only and are not intended to limit the technical solutions of the present invention.

[0025] It should be noted that, in this document, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. Furthermore, the terms "comprising," "including," or any other variations are intended to cover non-exclusive inclusion, such that an article or apparatus comprising a list of elements includes not only those elements but also other elements not explicitly listed.

[0026] In the description of this invention, it should be understood that the terms "thickness", "upper", "lower", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0027] Example 1 This invention provides a method for preparing heteroepitaxial single-crystal diamond based on a pre-laid nucleated carbon source, see [link to relevant documentation]. Figure 1 This includes the following steps S10-S50.

[0028] S10, such as Figure 2 As shown, heterogeneous substrate 1 was obtained.

[0029] In one example, obtaining the substrate involves sequentially ultrasonically cleaning the heterogeneous substrate 1 with acetone, anhydrous ethanol, and deionized water for 10–20 minutes each, in order to thoroughly remove organic, inorganic, and ionic contaminants from the substrate surface, providing an atomically clean surface for the subsequent formation of the nucleation carbon source layer 2.

[0030] In some examples, the heterostructure 1 may be, but is not limited to, a magnesium oxide substrate, a sapphire substrate, a strontium titanate substrate, or a single-crystal silicon-based yttrium oxide-stabilized zirconium oxide (YSZ / Si) composite substrate.

[0031] For example, the heterogeneous substrate 1 can be a circular substrate with a thickness of 0.5 to 3.5 mm and a diameter of 2 to 8 inches. In this way, the single-crystal diamond layer 8 obtained in the final preparation can be separated and used as a substrate for the wafer.

[0032] S20, such as Figure 3 As shown, a nucleation carbon source layer 2 is formed on one side of the heterogeneous substrate 1.

[0033] In one example, a nucleation carbon source layer 2 can be formed on the cleaned heterogeneous substrate 1 by using a chemical vapor deposition process or a polymer-assisted transfer process.

[0034] For example, the material of the nucleation carbon source layer 2 can be graphite or graphene.

[0035] In one example, the thickness of the nucleation carbon source layer 2 is 5–50 nm.

[0036] S30, such as Figure 4 As shown, an iridium metal layer 3 is formed on the side of the nucleation carbon source layer 2 away from the heterogeneous substrate 1. Specifically, an iridium metal layer 3 is formed on the surface of the nucleation carbon source layer 2, which completely covers the nucleation carbon source layer 2.

[0037] For example, the iridium metal layer 3 can be formed using magnetron sputtering, electron beam evaporation, or pulsed laser deposition. The actual process is not limited to the processes listed above.

[0038] For example, the thickness of the iridium metal layer 3 is 15–50 nm. In this embodiment, the thicknesses of both the nucleation carbon source layer 2 and the iridium metal layer 3 cannot be too large. On the one hand, if the thickness of the nucleation carbon source layer 2 is too large, it will affect the quality of the subsequently formed iridium metal layer 3; at the same time, if the nucleation carbon source layer 2 is too thick, the energy provided by the bias treatment in step S40 will not be sufficient to break the chemical bonds of the nucleation carbon source layer 2, thereby preventing the precipitation of diamond nuclei from the upper surface of the iridium metal layer 3; and increasing the energy of the bias treatment will place higher demands on the microwave plasma chemical vapor deposition equipment, increasing the cost of the equipment. On the other hand, if the thickness of the iridium metal layer 3 is too large, it will directly affect the precipitation and formation of the diamond nucleation layer 6 in step S40 of the microwave plasma chemical vapor deposition process, and may even cause the nucleation carbon source layer 2 to be difficult to precipitate, resulting in nucleation failure.

[0039] Furthermore, the thickness of the nucleated carbon source layer 2 is 5–15 nm, and the thickness of the iridium metal layer 3 is 15–25 nm.

[0040] S40, such as Figure 5 As shown, a microwave plasma chemical vapor deposition process is used to introduce a carbon-free precursor process gas 5; and a bias voltage is applied to the side of the heterogeneous substrate 1 away from the nucleation carbon source layer 2 and the side of the iridium metal layer 3 away from the nucleation carbon source layer 2, so that the carbon source of the nucleation carbon source layer 2 is precipitated from the iridium metal layer 3, and a diamond nucleation layer 6 is formed on the side of the iridium metal layer 3 away from the heterogeneous substrate 1.

[0041] In one example, step S40 specifically includes: S41. Define the sample obtained in step S30 as the first sample; place the first sample in a microwave plasma chemical vapor deposition apparatus; wherein, the heterogeneous substrate 1 is close to the first metal electrode plate 41, and the iridium metal layer 3 is close to the second metal electrode plate 42. S42. Reduce the cavity pressure of the microwave plasma chemical vapor deposition equipment to less than or equal to 0.001 mbar; S43. Introduce hydrogen (H2) into the microwave plasma chemical vapor deposition equipment at a flow rate of 100–800 sccm; when the cavity pressure of the microwave plasma chemical vapor deposition equipment reaches 10–25 mbar, turn on the microwave source. S44. When the microwave plasma chemical vapor deposition equipment reaches the preset parameters, a negative voltage is applied to the first metal electrode plate 41, and a positive voltage is applied to the second metal electrode plate 42 for bias treatment; the bias treatment time is 5 to 120 minutes. For example, the preset parameters are: the cavity gas pressure of the microwave plasma chemical vapor deposition equipment is 20 to 100 mbar, the microwave power is 600 to 2500 W, and the surface temperature of the side of the first sample away from the heterogeneous substrate 1 is 400 to 600°C. In other words, bias treatment is performed under the condition that the above preset parameters are met.

[0042] S50, such as Figure 6 and Figure 7 As shown, a single-crystal diamond layer 8 is obtained by using microwave plasma chemical vapor deposition (MSCVD) to introduce carbon-containing precursor process gas 7 and grow it on the diamond nucleation layer 6.

[0043] In one example, step S50 includes: S51. Define the sample processed in step S40 as the second sample; place the second sample in a microwave plasma chemical vapor deposition apparatus; S52. Adjust the cavity gas pressure of the microwave plasma chemical vapor deposition equipment to 120-200 mbar, the microwave power to 3000-5000 W, and the surface temperature of the side of the second sample away from the heterogeneous substrate 1 to 800-1000℃. S53. Methane (CH4), oxygen (O2), and nitrogen (N2) are introduced into a microwave plasma chemical vapor deposition (PCVDC) apparatus. The flow rates of methane (CH4) are 7–72 sccm, oxygen (O2) are 0.5–20 sccm, and nitrogen (N2) are 0.001–4 sccm. Single-crystal diamond is grown for 48–168 hours. After growth is complete, the introduction of CH4, O2, and N2 is stopped, and the chamber pressure and power are slowly reduced to prevent the heteroepitaxial diamond substrate from cracking due to thermal stress.

[0044] In one example, the thickness of the single-crystal diamond layer 8 obtained by growth is 0.5–3 mm.

[0045] The present invention provides a method for preparing heteroepitaxial single-crystal diamond based on pre-laid nucleation carbon sources, which aims to improve the nucleation process in heteroepitaxial growth of single-crystal diamond. By eliminating the introduction of carbon sources during the nucleation process, the nucleation quality is greatly improved, achieving high-quality heteroepitaxial growth and thus significantly improving the quality of heteroepitaxial single-crystal diamond.

[0046] In this embodiment, by pre-depositing a nucleation carbon source layer 2 under the iridium metal layer 3, the traditional heteroepitaxial growth process of injecting carbon-containing groups into the iridium metal and then precipitating them is simplified to directly precipitating the carbon source in the nucleation carbon source layer 2 under the iridium metal. This significantly reduces the damage to the iridium metal on the hetero substrate 1 during nucleation, thereby optimizing the subsequent heteroepitaxial growth process.

[0047] Because the carbon source changes from carbon-containing groups in the microwave plasma chemical vapor deposition (IPV) atmosphere to the nucleation carbon source layer 2 located beneath the iridium metal layer 3, a carbon-free precursor process gas is introduced during the nucleation process of heteroepitaxial growth. This prevents the formation of unnecessary diamond particles during nucleation, improving the crystal orientation consistency of diamond nuclei in the diamond nucleation layer 6. This makes it easier for diamond nuclei to merge during subsequent growth, significantly optimizing the quality of single-crystal diamond prepared by heteroepitaxial growth. Furthermore, since the carbon source during nucleation is provided by a carbon-free precursor process gas, the nucleation and growth processes in diamond heteroepitaxial growth can be distinguished by whether or not a carbon-containing precursor process gas is introduced. This is more conducive to the research and optimization of subsequent diamond heteroepitaxial processes, promoting industrial upgrading, process standardization, and large-scale production, further laying the foundation for the application of heteroepitaxial single-crystal diamond.

[0048] Example 2 The present invention also provides a heteroepitaxial single-crystal diamond based on a pre-laid nucleation carbon source, which is prepared by the method of any of the above embodiments. The heteroepitaxial single-crystal diamond based on a pre-laid nucleation carbon source includes a heterostructure substrate 1, a nucleation carbon source-iridium metal composite layer, a diamond nucleation layer 6, and a single-crystal diamond layer 8 stacked sequentially.

[0049] Example 3 See Figure 1 A schematic flowchart of a method for preparing heteroepitaxial single-crystal diamond based on a pre-laid nucleation carbon source, provided in an embodiment of the present invention, includes: Step S10, as follows Figure 2 As shown, a 2-inch diameter, 1.5mm thick strontium titanate substrate was prepared as the heterostructure substrate 1 for growing single-crystal diamond. The selected strontium titanate substrate was ultrasonically cleaned sequentially with acetone, anhydrous ethanol, and deionized water for 15 minutes each, for a total of 45 minutes.

[0050] Step S20, as follows Figure 3 As shown, graphene is used to form an ultrathin nucleation carbon source layer 2 on a heterogeneous substrate 1 by a transfer method; the thickness of the nucleation carbon source layer 2 is 10 nm.

[0051] Step S30, as Figure 4As shown, an iridium metal layer 3 is deposited on a heterogeneous substrate 1 having a nucleation carbon source layer 2, such that the iridium metal layer 3 completely covers the nucleation carbon source layer 2 on the heterogeneous substrate 1.

[0052] Specifically, an iridium metal layer 3 was prepared on the side of the nucleation carbon source layer 2 away from the heterogeneous substrate 1 using magnetron sputtering. The growth atmosphere was argon, the growth power was 125W, the growth temperature was 800℃, and the thickness of the grown iridium metal layer was 20nm.

[0053] Step S40, as Figure 5 As shown, a diamond nucleation process is performed, the process conditions are adjusted, a gas without carbon groups (carbon-free precursor process gas 5) is introduced, and a bias voltage is applied above and below the first sample prepared in step S30 to cause the carbon source to precipitate from the iridium metal layer 3, forming a diamond nucleation layer 6 with a consistent crystal orientation. The diamond nucleation layer 6 is located on the side of the iridium metal layer 3 away from the heterostructure substrate 1.

[0054] Specifically, this includes assembling two metal electrode plates (first metal electrode plate 41 and second metal electrode plate 42) in an MPCVD (microwave plasma chemical vapor deposition) device for heteroepitaxial growth.

[0055] The first sample is placed in the MPCVD equipment, wherein the heterogeneous substrate 1 is close to the first metal electrode plate 41 and the iridium metal layer 3 is close to the second metal electrode plate 42.

[0056] The chamber pressure of the MPCVD equipment is reduced to 0.001 mbar or below; H2 is introduced into the MPCVD equipment at a flow rate of 200 sccm; When the cavity pressure of the MPCVD equipment reaches 15 mbar, turn on the microwave source.

[0057] The chamber pressure of the MPCVD equipment was increased to 40 mbar, the microwave power was set to 800 W, and the surface temperature of the first sample, away from the heterogeneous substrate 1, was set to 450°C. After the process environment stabilized, a bias voltage was applied to the metal electrode plates 42 and 41, respectively. A positive voltage was applied to the second metal electrode plate 42 and a negative voltage was applied to the first metal electrode plate 41. The bias treatment was then initiated, and the treatment time for the first sample was 60 minutes.

[0058] Step S50, as follows Figure 6 As shown, the second sample obtained in step S40 is subjected to a diamond growth process. The process conditions are adjusted, and a gas containing carbon groups (carbon-containing precursor process gas 7) is introduced. On the diamond nucleation layer 6 with a consistent crystal orientation, a diameter-expanding diamond growth process is used to merge the crystal nuclei and prepare a single-crystal diamond layer 8, thereby realizing the preparation of a large-size single-crystal diamond substrate.

[0059] Specifically, this includes: adjusting the chamber pressure of the MPCVD equipment to 180 mbar, the microwave power to 4000 W, and the surface temperature of the second sample on the side away from the heterogeneous substrate 1 to 920 °C. CH4, O2, and N2 were introduced into the MPCVD equipment; the flow rate of CH4 was 12 sccm, the flow rate of O2 was 1 sccm, and the flow rate of N2 was 0.05 sccm, with a growth time of 72 hours. This diamond growth process was used to fuse the crystal nuclei and grow to a thickness of 2 mm. After growth was complete, the introduction of CH4, O2, and N2 was stopped, and the chamber pressure and power of the MPCVD equipment were slowly reduced to ensure that the heteroepitaxial diamond substrate would not fracture due to thermal stress.

[0060] In this embodiment, the cavity pressure of the MPCVD equipment is evacuated to 20 Torr, and the power is reduced to 600W. After the cavity temperature of the MPCVD equipment stabilizes, the microwave source is turned off. The supply of CH4, O2, and N2 is stopped, and the cavity pressure of the MPCVD equipment is evacuated to 0.001 mbar, and the pump is turned off. Air is introduced into the cavity of the MPCVD equipment to break the vacuum, and the heteroepitaxial diamond is removed from the cavity of the MPCVD equipment, completing the heteroepitaxial diamond growth process.

[0061] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0062] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for preparing heteroepitaxial single-crystal diamond based on a pre-laid nucleated carbon source, characterized in that, Includes the following steps: S10, Obtain the heterogeneous substrate; S20. A nucleation carbon source layer is formed on one side of the heterogeneous substrate; S30. An iridium metal layer is formed on the side of the nucleation carbon source layer away from the heterogeneous substrate; S40. A microwave plasma chemical vapor deposition process is used to introduce a carbon-free precursor process gas; and a bias voltage is applied to the side of the heterogeneous substrate away from the nucleation carbon source layer and the side of the iridium metal layer away from the nucleation carbon source layer, so that the carbon source of the nucleation carbon source layer is precipitated from the iridium metal layer, and a diamond nucleation layer is formed on the side of the iridium metal layer away from the heterogeneous substrate. S50. A single-crystal diamond layer is grown on the diamond nucleation layer by introducing a carbon-containing precursor process gas using microwave plasma chemical vapor deposition.

2. The method for preparing heteroepitaxial single-crystal diamond based on a pre-laid nucleated carbon source according to claim 1, characterized in that, In step S20, the formation of the nucleation carbon source layer includes using a chemical vapor deposition process or a polymer-assisted transfer process.

3. The method for preparing heteroepitaxial single-crystal diamond based on a pre-laid nucleated carbon source according to claim 2, characterized in that, The material of the nucleation carbon source layer is graphite or graphene.

4. The method for preparing heteroepitaxial single-crystal diamond based on a pre-laid nucleated carbon source according to claim 1, characterized in that, Step S40 includes: The sample obtained in step S30 is defined as the first sample; the first sample is placed in a microwave plasma chemical vapor deposition apparatus; wherein, the heterogeneous substrate is close to the first metal electrode plate, and the iridium metal layer is close to the second metal electrode plate; The cavity pressure of the microwave plasma chemical vapor deposition equipment is evacuated to less than or equal to 0.001 mbar; Hydrogen gas is introduced into the microwave plasma chemical vapor deposition equipment at a flow rate of 100–800 sccm; when the cavity pressure of the microwave plasma chemical vapor deposition equipment reaches 10–25 mbar, the microwave source is turned on. When the microwave plasma chemical vapor deposition equipment reaches the preset parameters, a negative voltage is applied to the first metal electrode plate and a positive voltage is applied to the second metal electrode plate for bias treatment; the bias treatment time is 5 to 120 minutes.

5. The method for preparing heteroepitaxial single-crystal diamond based on a pre-laid nucleated carbon source according to claim 4, characterized in that, The preset parameters are: the cavity gas pressure of the microwave plasma chemical vapor deposition equipment is 20-100 mbar, the microwave power is 600-2500 W, and the surface temperature of the first sample on the side away from the heterogeneous substrate is 400-600 °C.

6. The method for preparing heteroepitaxial single-crystal diamond based on a pre-laid nucleated carbon source according to claim 1, characterized in that, Step S50 includes: The sample processed in step S40 is defined as the second sample; the second sample is placed in a microwave plasma chemical vapor deposition apparatus. The cavity gas pressure of the microwave plasma chemical vapor deposition equipment is adjusted to 120-200 mbar, the microwave power is 3000-5000 W, and the surface temperature of the side of the second sample away from the heterogeneous substrate is 800-1000 °C. Methane, oxygen, and nitrogen are introduced into a microwave plasma chemical vapor deposition apparatus; wherein the flow rate of methane is 7–72 sccm, the flow rate of oxygen is 0.5–20 sccm, and the flow rate of nitrogen is 0.001–4 sccm, for the growth of single-crystal diamond, and the growth time is 48–168 h.

7. The method for preparing heteroepitaxial single-crystal diamond based on a pre-laid nucleated carbon source according to any one of claims 1-6, characterized in that, The thickness of the nucleation carbon source layer is 5–50 nm; the thickness of the iridium metal layer is 15–50 nm. The thickness of the single-crystal diamond layer is 0.5–3 mm.

8. The method for preparing heteroepitaxial single-crystal diamond based on a pre-laid nucleated carbon source according to claim 7, characterized in that, The heterogeneous substrate is a magnesium oxide substrate, a sapphire substrate, a strontium titanate substrate, or a single-crystal silicon-based yttrium oxide-stabilized zirconium oxide film composite substrate.

9. The method for preparing heteroepitaxial single-crystal diamond based on a pre-laid nucleated carbon source according to claim 7, characterized in that, The iridium metal layer is formed using magnetron sputtering, electron beam evaporation, or pulsed laser deposition.

10. A heteroepitaxial single-crystal diamond based on a pre-laid nucleated carbon source, characterized in that, It is obtained by the preparation method described in any one of claims 1-9.

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