Diamond crystal and growth deposition device and growth method thereof

Abstract

The invention discloses a diamond crystal as well as a growth deposition device and a growth method thereof, and belongs to the technical field of vapor deposition. The diamond crystal meets the following conditions that a, the thickness difference between the edge area and the center area of the crystal is smaller than or equal to 10 micrometers; b, total dislocation defect density lt; 105 / cm < 2 >; c, the thickness of the crystal is 0.3 to 10 mm; and d, the absolute value of the stress is lower than 20 MPa. By using a structure for actively adjusting the height of the surface and the edge of the molybdenum support and combining a specific growth process, the growth method for realizing the constant height of the crystal surface and the edge of the molybdenum support and inhibiting the edge effect is realized, and the high-quality and few-crack diamond crystal is obtained.

Description

Technical Field

[0001] This application relates to a diamond crystal and its growth deposition apparatus and method, belonging to the field of vapor deposition technology. Background Technology

[0002] Microwave plasma chemical vapor deposition (MPCVD) has become the most favored diamond growth technology in scientific research and high-end industrial applications due to its comprehensive advantages, including being pollution-free, highly controllable, and capable of growing high-quality and diverse diamond materials. During diamond growth, a molybdenum support, due to its chemical stability, is typically used as the diamond growth base and placed on a copper substrate. The copper substrate has an internal water-cooling system for heat dissipation. The quality of diamond growth is highly dependent on the uniformity of the plasma.

[0003] However, as the deposition process continues, the diamond crystal thickens, leading to the following defects: ① Plasma distortion: The increased crystal height causes the electric field lines to bend towards the center, resulting in a significantly higher electric field strength at the edges than at the center, inducing uncontrolled heterogeneous crystal growth (parasitic growth). ② Thermal field fluctuations: After the crystal protrudes from the tray, the heat dissipation environment on its sides changes abruptly, leading to an increased radial temperature difference, which easily causes stress cracking of the crystal. ③ Thickness bottleneck: Due to the change in height altering the optimal growth process window, the thickness of a single growth is severely limited, making it difficult to achieve large-size, high-quality, and thick crystals. Summary of the Invention

[0004] To address the aforementioned challenges, this invention provides a diamond crystal and its growth deposition apparatus and method. By using a structure that actively adjusts the height between the crystal surface and the edge of the molybdenum support, combined with a specific growth process, a growth method is achieved that maintains a constant height between the crystal surface and the edge of the molybdenum support, suppressing edge effects, and thus obtaining a high-quality diamond crystal with fewer cracks.

[0005] According to the first aspect of this application, this application provides a diamond crystal that satisfies the following conditions: a. The thickness difference between the edge region and the central region of the crystal is ≤10μm; b. Total dislocation defect density <10 5 / cm 2 ; c. The thickness of the crystal is 0.3-10 mm; d. The absolute value of the stress is less than 20 MPa.

[0006] The diamond crystal of this application maintains a high-quality single-crystal structure in both the edge and center regions, with minimal thickness difference between the edge and center, very few uncontrolled impurities at the edge, and highly consistent crystallographic orientation. This avoids the impurity region from acting as an impurity diffusion channel or stress concentration point, thereby ensuring the performance consistency of the entire crystal.

[0007] Specifically, the edge region is the outer region located at a distance of 1 / 2 radius from the geometric center of the crystal.

[0008] Specifically, the central region is the internal region located at a distance of 0-1 / 2 radius from the geometric center of the crystal.

[0009] Optionally, the TTV of the upper surface of the crystal is <10μm, and the TTV of the lower surface is <10μm.

[0010] Optionally, the crystal has no cracks or the number of cracks larger than 10 μm in the crystal is 1.

[0011] According to a second aspect of this application, this application provides a diamond growth and deposition apparatus, comprising: External molybdenum support assembly: From top to bottom, the external molybdenum support, the outer base, and the outer support column are connected in sequence. The outer base and the outer support column are detachably connected. The external molybdenum support has an opening in the center. Inner molybdenum support assembly: The inner molybdenum support assembly is located at the center of the outer molybdenum support assembly, and is connected from top to bottom to the inner molybdenum support, inner base and inner support column. The inner base and the inner support column are detachably connected. The inner molybdenum support is located in the central opening of the outer molybdenum support, and the outer molybdenum support and the inner molybdenum support are arranged along the same central axis. There is a gap between the inner molybdenum support and the outer molybdenum support. Drive system: The drive system is connected to the inner support column, and the drive system is used to drive the inner support column to lift, rotate and move. The outer support column and the inner support column are equipped with spiral circulating water cooling channels.

[0012] In the growth deposition apparatus of this application, the outer molybdenum support assembly and the inner molybdenum support assembly are independent of each other. The outer molybdenum support is fixed and provides a reference surface, while the inner molybdenum support achieves dynamic height compensation. The two work together to ensure the stability of the plasma field and realize the active adjustment of the growth interface. The drive system can drive the inner support column to achieve both lifting and rotation functions with high control precision, providing a reliable actuator for dynamic compensation. The rotation of the inner support column can make the crystal surface uniformly contact the plasma ball and eliminate radial temperature difference. The inner and outer copper bases are detachably connected to the support column, which facilitates the replacement of the inner molybdenum support according to the seed crystal size, improves the adaptability of the equipment, and reduces replacement costs.

[0013] Optionally, the diameter of the inner molybdenum holder is the same as the diameter of the seed crystal.

[0014] The inner molybdenum support is of the same diameter as the seed crystal, making the edge of the seed crystal flush with the edge of the molybdenum support. This avoids electric field concentration points caused by size mismatch and suppresses the formation of edge impurities from the source.

[0015] Optionally, the distance between the inner molybdenum support and the outer molybdenum support is 'a', and the value of 'a' ranges from 0.05 to 1.0 mm.

[0016] Setting this gap range ensures smooth movement of the inner molybdenum support, while the tiny gap combined with a sealing structure minimizes the risk of plasma infiltration. It also allows space for the thermal expansion of the substrate and prevents thermal short circuits caused by direct contact between the inner and outer molybdenum supports.

[0017] Optionally, the lifting stroke of the drive system is 0.1mm-20mm, and the speed at which the inner bearing column is driven to rotate is 0.1-20rpm.

[0018] The lifting stroke of the drive system can cover the entire growth cycle of the seed crystal without the need for mid-process stoppage for adjustment; the rotation stroke can adapt to various seed crystal growth requirements and meet specific process needs.

[0019] Optionally, the outer diameter of the outer molybdenum support is 100-300 mm.

[0020] Optionally, the drive system uses a servo motor for driving.

[0021] According to a third aspect of this application, this application provides a dynamically height-compensated MPCVD diamond growth method, which employs the diamond growth deposition apparatus described in any of the preceding claims, and includes the following steps: (1) Pretreatment: Place the seed crystal on the inner molybdenum support, evacuate the chamber, and then perform in-situ etching and cleaning on the surface of the seed crystal; (2) Growth: In a hydrogen atmosphere, methane, oxygen, nitrogen and argon are introduced in sequence to make the seed crystal grow to a thickness of 1-10 mm under a pressure of 5k-30kPa and a temperature of 800-1200℃. During the growth process, the inner molybdenum support is driven to rotate and descend by the drive system, so that the diamond growth surface is not higher than the upper surface of the outer molybdenum support. (3) Annealing: After growth, turn off methane and keep the crystal temperature at 800-1200℃; then turn off nitrogen, oxygen and argon and anneal the crystal at 800-1000℃ for 1-10 hours in a hydrogen atmosphere, cool down and obtain the crystal.

[0022] This method utilizes a dynamic height compensation mechanism to synchronously lower the inner molybdenum support during growth, ensuring a constant height difference between the crystal growth surface and the support's reference plane. This prevents uncontrolled nucleation at the edges induced by electric field distortion, thus avoiding the formation of a heterogeneous layer. Simultaneously, it keeps the crystal in an optimal heat dissipation position, preventing abrupt changes in lateral heat dissipation caused by the protruding support. The rotation function ensures uniform contact between the crystal surface and the plasma sphere, eliminating radial temperature differences and preventing localized overheating due to plasma standing wave effects, achieving comprehensive and uniform crystal growth.

[0023] In-situ etching and cleaning during pretreatment can effectively remove the oxide layer, contaminants, and mechanical damage layer on the seed crystal surface, providing a clean substrate for high-quality epitaxy.

[0024] In addition, the design of the inner molybdenum support and the seed crystal having the same diameter can eliminate the edge step effect, and the tiny gap between the outer molybdenum support and the inner molybdenum support can effectively suppress the edge discharge phenomenon and improve the crystal quality.

[0025] Optionally, the seed crystal in step (1) is a single-crystal diamond seed crystal or a polycrystalline diamond seed crystal.

[0026] Optionally, the minimum linear size of the diamond seed crystal in step (1) is 1-50 mm.

[0027] Optionally, the substrate of the single-crystal diamond seed crystal is at least one of diamond single-crystal substrate, Si substrate, Al2O3 substrate, 3C-SiC substrate, and YSZ substrate.

[0028] Optionally, the substrate of the polycrystalline diamond seed crystal is at least one of a Si substrate, an Al2O3 substrate, and a SiC substrate.

[0029] Optionally, the minimum linear dimension of each of the substrates is 1-50 mm.

[0030] Optionally, the in-situ etching and cleaning time in step (1) is 5-30 min.

[0031] Optionally, the rotation speed of the inner molybdenum support in step (2) is 0.1-20 rpm.

[0032] Within this rotational speed range, uniform plasma coverage can be achieved while avoiding centrifugal force interference or mechanical vibration caused by high-speed rotation, thus enabling high-quality crystal growth.

[0033] Optionally, the molybdenum support descends at a rate of 0.1-100 μm / h.

[0034] Within this descent speed range, it is possible to ensure that the compensation speed is synchronized with the crystal growth speed in real time, so that the diamond growth surface and the outer molybdenum support reference surface maintain a constant height difference.

[0035] Optionally, the height difference between the diamond growth surface and the upper surface of the outer molybdenum support in step (2) is d, and the value of d ranges from 0 to 2.0 mm.

[0036] Maintaining the diamond growth surface and the upper surface of the outer molybdenum support within a range of 0-2.0 mm ensures that the crystal growth surface is always in the optimal position of the plasma sheath, resulting in uniform electric field intensity. This avoids edge discharge and weak field problems at the center, and also ensures that the heat dissipation environment on the crystal side is consistent with the initial state, eliminating radial temperature differences and suppressing the accumulation of thermal stress.

[0037] During the growth process, the height difference between the growth surface and the outer molybdenum support reference surface can be visually observed through the observation window. The descent speed of the inner molybdenum support can also be adjusted to ensure that the height difference d between the growth surface and the molybdenum support reference surface is always maintained.

[0038] Preferably, the value of d is in the range of 0.1-1.0 mm.

[0039] Optionally, the operation of sequentially introducing methane, oxygen, nitrogen, and argon in step (2) is as follows: S1: In a hydrogen atmosphere, introduce methane with a volume fraction of 3-5% for 1-2 hours; S2: Reduce the volume fraction of methane to 1-2%, and introduce oxygen with a volume fraction of 0.1-2% for 5-10 minutes; S3: Introduce nitrogen gas with a volume fraction of 0.1-2% for 5-10 minutes; S4: Finally, introduce argon gas with a volume fraction of 0.1-2%.

[0040] First, a high concentration of methane is introduced to provide a sufficient carbon source, promote rapid nucleation, shorten the nucleation time, and improve the interfacial bonding strength. Then, the carbon source concentration is reduced to suppress the formation of non-diamond phases, ensuring the crystal quality of long-term epitaxial growth and obtaining a low-defect thick film. Simultaneously, oxygen is introduced to begin etching sp during the nucleation stage. 2 Non-diamond carbon reacts to generate CO / CO2 gas, which volatilizes, reducing the accumulation of interface defects and improving crystal purity. The nitrogen gas introduced afterward promotes high-speed growth and improves deposition efficiency. At the same time, the operation of introducing nitrogen gas after nucleation stabilization can avoid orientation disorder caused by nitrogen gas interference during the nucleation stage. After plasma stabilization, argon gas is introduced to further optimize the shape and uniformity of plasma spheres and improve the growth consistency of large-area substrates.

[0041] Optionally, the cooling rate in step (3) is 1-20℃ / min.

[0042] Optionally, borane gas or phosphine gas may also be introduced in step (2).

[0043] Preferably, the volume fraction of the borane gas is 0.1-2%.

[0044] Preferably, the volume fraction of the phosphine gas is 0.1-2%.

[0045] The beneficial effects of this application include, but are not limited to: 1. The diamond crystal according to this application maintains a high-quality single-crystal structure in both the edge and center regions, with minimal thickness difference between the edge and center, very few uncontrolled impurities at the edge, and highly consistent crystallographic orientation.

[0046] 2. According to the diamond growth and deposition apparatus of this application, a closed-loop control system drives the molybdenum support to sink synchronously, ensuring that the diamond growth interface remains flush with the reference plane of the molybdenum support. This ensures that the seed crystal surface and the edge of the inner molybdenum support are at the same height, avoiding electric field concentration or edge discharge phenomena caused by size mismatch, effectively suppressing the formation of edge impurities, and improving crystal uniformity.

[0047] 3. According to the diamond growth and deposition apparatus of this application, the lifting and rotation functions of the inner support column can meet the requirements of plasma uniformity at different growth stages. The rotation can make the seed crystal surface uniformly contact the plasma ball, avoiding local overheating or uneven growth.

[0048] 4. According to the dynamic height compensation MPCVD diamond growth method of this application, the inner molybdenum support is synchronously lowered during the growth process through the dynamic height compensation mechanism, which ensures that the crystal growth surface always maintains a constant height difference with the molybdenum support reference plane, avoids uncontrolled nucleation at the edge induced by electric field distortion, and avoids the formation of a heterogeneous layer. At the same time, it keeps the crystal in the optimal heat dissipation position and avoids abrupt changes in side heat dissipation caused by the protruding tray. Attached Figure Description

[0049] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is an overall diagram of the diamond growth and deposition apparatus according to Embodiment 1 of this application; Figure 2 This is a cross-sectional view of the diamond growth and deposition apparatus according to Embodiment 1 of this application; Figure 3 This is a cross-sectional view of the diamond growth and deposition apparatus according to Embodiment 1 of this application. Figure 2 A partial cross-sectional view of section A in the middle; Figure 4 This is a diagram of a diamond single crystal grown using the dynamic height-compensated MPCVD diamond growth method described in Embodiment 2 of this application. Figure 5 This image shows a diamond single crystal grown using the MPCVD diamond growth method with dynamic height compensation as described in Comparative Example 4 of this application. Figure 6This is a diagram of a diamond polycrystalline crystal grown using the dynamic height-compensated MPCVD diamond growth method described in Embodiment 3 of this application. Figure 7 This is a diagram of a diamond polycrystalline crystal obtained by the growth method described in Comparative Example 1 of this application.

[0050] List of components and reference numerals: 1. Outer molybdenum support; 2. Outer base; 3. Outer bearing column; 4. Inner molybdenum support; 5. Inner base; 6. Inner bearing column; 7. Drive system; 8. Circulating water cooling channel; 9. Diamond growth surface; 10. Upper surface of outer molybdenum support; 11. Seed crystal. Detailed Implementation

[0051] To more clearly illustrate the overall concept of this application, a detailed explanation is provided below with reference to the accompanying drawings.

[0052] To better understand the above-mentioned objectives, features, and advantages of this application, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0053] Many specific details are set forth in the following description in order to provide a full understanding of this application. However, this application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of this application is not limited to the specific embodiments disclosed below.

[0054] Furthermore, it should be understood in the description of this application that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application 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. Therefore, they should not be construed as limitations on this application.

[0055] Furthermore, 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 technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0056] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0057] In this application, unless otherwise expressly specified and limited, the "above" or "below" of the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. In the description of this specification, references to terms such as "an 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 this application. 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 can be combined in any suitable manner in one or more embodiments or examples.

[0058] Example 1 refer to Figure 1 , Figure 2 and Figure 3 The embodiments of this application disclose a diamond growth deposition apparatus, an outer molybdenum support assembly: from top to bottom, an outer molybdenum support 1, an outer base 2 and an outer support column 3 are connected in sequence, the outer base 2 and the outer support column 3 are detachably connected, and the outer molybdenum support 1 has an opening at its center; Inner molybdenum support assembly: The inner molybdenum support assembly is located at the center of the outer molybdenum support assembly, and is connected from top to bottom to the inner molybdenum support 4, the inner base 5, and the inner support column 6. The inner base 5 and the inner support column 6 are detachably connected. The inner molybdenum support 4 is located in the central opening of the outer molybdenum support 1, and the outer molybdenum support 1 and the inner molybdenum support 4 are arranged along the same central axis. There is a gap between the inner molybdenum support 4 and the outer molybdenum support 1. Drive system: The drive system 7 is connected to the inner support column 6, and the drive system 7 is used to drive the inner support column 6 to lift and rotate; The outer support column 3 and the inner support column 6 are provided with spiral circulating water cooling channels 8.

[0059] In one embodiment, the diameter of the inner molybdenum holder 4 is the same as the diameter of the seed crystal 11.

[0060] In one embodiment, the distance between the inner molybdenum support 4 and the outer molybdenum support 1 is 'a', and the value of 'a' ranges from 0.05 to 1.0 mm.

[0061] In one embodiment, the lifting stroke of the drive system 7 is 0.1mm-20mm, and the speed at which the inner bearing column 6 is driven to rotate is 0.1-20rpm.

[0062] In one embodiment, the outer diameter of the outer molybdenum support 1 is 100-300 mm.

[0063] In one implementation, the drive system 7 is driven by a servo motor.

[0064] In one embodiment, the detachable connection is a threaded connection with a sealing gasket at the connection point.

[0065] Example 2 below 9. Comparative Examples 1-4 are diamond growth methods performed using the apparatus in Example 1, so the corresponding components are no longer labeled.

[0066] Example 2 This embodiment uses the diamond growth and deposition apparatus of Example 1 to realize the MPCVD diamond growth method with dynamic height compensation, including the following steps: (1) Pretreatment: A single-crystal diamond seed crystal (diamond single-crystal substrate) with a minimum linear dimension of 1 mm is placed on the inner molybdenum support, and the chamber is evacuated to 1.0 × 10⁻⁶ mm. -3 After Pa is below, high-purity hydrogen gas is introduced at a flow rate of 1000 sccm, and microwave-excited plasma is turned on to perform in-situ etching and cleaning of the seed crystal surface at 10 kW and 1100℃ for 5 min. (2) Growth: S1: In a hydrogen atmosphere, methane with a volume fraction of 3% is introduced for 2 hours at a flow rate of 22 sccm; S2: Reduce the volume fraction of methane to 1%, and introduce oxygen with a volume fraction of 2% for 5-10 minutes at a flow rate of 17 sccm. S3: Introduce nitrogen gas with a volume fraction of 2% for 5 minutes at a flow rate of 31 sccm; S4: Finally, introduce argon gas with a volume fraction of 2% at a flow rate of 40 sccm.

[0067] The diamond seed crystal was grown to a thickness of 1 mm under a pressure of 5 kPa and a temperature of 800 °C. During the growth process, the inner molybdenum support is driven to rotate and descend by the drive system. The rotation speed is 0.1 rpm and the descent speed is 0.1 μm / h, so that the diamond growth surface and the upper surface of the outer molybdenum support maintain a constant height difference d of 0 mm. (3) Annealing: After growth, methane is slowly shut off and the crystal temperature is maintained at 800℃; then nitrogen, oxygen and argon are shut off and the crystal is annealed at 800℃ for 10h in a hydrogen atmosphere. After the annealing is completed, the temperature is reduced by 1℃ / min.

[0068] Example 3 This embodiment uses the diamond growth and deposition apparatus of Example 1 to realize the MPCVD diamond growth method with dynamic height compensation, including the following steps: (1) Pretreatment: A polycrystalline diamond seed crystal (Si substrate) with a minimum linear dimension of 50 mm is placed on the inner molybdenum support, and the chamber is evacuated to 1.0 × 10⁻⁶ mm. -3 After Pa is below, high-purity hydrogen gas is introduced at a flow rate of 1000 sccm, and microwave-excited plasma is turned on to perform in-situ etching and cleaning of the seed crystal surface at 1 kW and 800℃ for 30 min. (2) Growth: S1: In a hydrogen atmosphere, 5% methane by volume is introduced for 1 hour at a flow rate of 22 sccm. S2: Reduce the volume fraction of methane to 2%, and introduce oxygen with a volume fraction of 0.1% for 5-10 minutes at a flow rate of 17 sccm; S3: Introduce nitrogen gas with a volume fraction of 0.1% for 10 minutes at a flow rate of 31 sccm; S4: Finally, argon gas with a volume fraction of 0.1% and a flow rate of 40 sccm is introduced, and borane gas with a volume fraction of 0.1% is introduced at the same time to grow the diamond seed crystal to a thickness of 10 mm under a pressure of 30 kPa and a temperature of 1200℃. During the growth process, the inner molybdenum support is driven to rotate and descend by the drive system. The rotation speed is 20 rpm and the descent speed is 100 μm / h, so that the diamond growth surface and the upper surface of the outer molybdenum support maintain a constant height difference d of 2.0 mm. (3) Annealing: After growth, methane is slowly shut off and the crystal temperature is maintained at 1200℃; then nitrogen, oxygen and argon are shut off and the crystal is annealed at 1000℃ for 1 hour in a hydrogen atmosphere. After the annealing is completed, the temperature is reduced at 20℃ / min.

[0069] Example 4 This embodiment uses the diamond growth and deposition apparatus of Example 1 to realize the MPCVD diamond growth method with dynamic height compensation, including the following steps: (1) Pretreatment: A polycrystalline diamond seed crystal (Si substrate) with a minimum linear dimension of 40 mm is placed in the center of the inner molybdenum support, and the chamber is evacuated to 1.0 × 10⁻⁶ mm. -3 After Pa is below, high-purity hydrogen gas is introduced at a flow rate of 1000 sccm, and microwave-excited plasma is turned on to perform in-situ etching and cleaning of the seed crystal surface at 5 kW and 1000℃ for 10 min. (2) Growth: S1: In a hydrogen atmosphere, methane with a volume fraction of 4% is introduced for 1 hour at a flow rate of 22 sccm; S2: Reduce the volume fraction of methane to 1.5%, then introduce oxygen with a volume fraction of 1% for 5-10 minutes at a flow rate of 17 sccm; S3: Introduce nitrogen gas with a volume fraction of 1% for 10 minutes at a flow rate of 31 sccm; S4: Finally, argon gas with a volume fraction of 1% and a flow rate of 40 sccm is introduced to grow the diamond seed crystal under a pressure of 30 kPa, a temperature of 833℃ and a power of 6 kW until a 2.0 mm ultra-thick crystal is obtained. During the growth process, the inner molybdenum support is driven to rotate and descend by the drive system. The rotation speed is 12.5 rpm and the descent speed is 72 μm / h, so that the diamond growth surface and the upper surface of the outer molybdenum support maintain a constant height difference d of 1.0 mm. (3) Annealing: After growth, methane is slowly shut off and the crystal temperature is maintained at 833℃; then nitrogen, oxygen and argon are shut off and the crystal is annealed at 800℃ for 1 hour in a hydrogen atmosphere. After the annealing is completed, the temperature is reduced at 10℃ / min.

[0070] Example 5 The difference between this embodiment and embodiment 4 is that the speed at which the inner molybdenum support descends is 110 μm / h, while all other aspects are the same.

[0071] Example 6 The difference between this embodiment and embodiment 4 is that the rotation speed of the inner molybdenum support in step (2) is 24 rpm, while the rest are the same.

[0072] Example 7 The difference between this embodiment and embodiment 4 is that the volume fraction of methane in step S2 is not reduced to 1.5%, but is maintained at the volume fraction in step S1; all other aspects are the same.

[0073] Example 8 The difference between this embodiment and embodiment 4 is that the volume fraction of nitrogen in step S3 is 2.4%, while the rest are the same.

[0074] Example 9 The difference between this embodiment and embodiment 4 is that the volume fraction of argon in step S4 is 2.4%, while the rest are the same.

[0075] Comparative Example 1 The difference between this comparative example and Example 4 is that the inner molybdenum support does not rotate downward in step (2), but the rest are the same.

[0076] Comparative Example 2 The difference between this comparative example and Example 4 is that in step (2), the inner molybdenum support does not descend but only rotates; the rest are the same.

[0077] Comparative Example 3 The difference between this comparative example and Example 4 is that in step (2), the inner molybdenum support does not rotate but only descends; the rest are the same.

[0078] Comparative Example 4 The difference between this comparative example and Example 2 is that the inner molybdenum support does not rotate downward in step (2), but the rest are the same.

[0079] Test case The diamond crystals obtained in Examples 2-9 and Comparative Examples 1-4 were characterized for total dislocation density, crystal thickness, total volumetric TV (TTV), number of cracks, and absolute stress. The data are shown in Tables 1 and 2. The diamond crystals of Examples 2, 3, 4, and 5 were also observed. Figures 4-7 .

[0080] The total dislocation defect density was tested using an etching machine and an optical microscope; the crystal thickness was tested using a micrometer; the total volumetric TV (TTV) was tested using an FRT; the number of cracks was tested using a microscope; and the absolute stress value was tested using a Raman spectrometer.

[0081] Table 1

[0082] Table 2

[0083] Depend on Figures 4-7 It can be seen that the diamond growth deposition apparatus of the present invention realizes a diamond growth method with dynamic height compensation, which suppresses impurities at the edge of diamond crystals, reduces the overall substrate internal stress, reduces the generation of cracks, and improves product quality.

[0084] The above description is merely an embodiment of this application, and the scope of protection of this application is not limited to these specific embodiments, but is determined by the claims of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the technical concept and principles of this application should be included within the scope of protection of this application.

Claims

1. A diamond crystal, characterized in that, The following conditions must be met: a. The thickness difference between the edge region and the central region of the crystal is ≤10μm; b. Total dislocation defect density <10 5 / cm 2 ; c. The thickness of the crystal is 0.3-10 mm; d. The absolute value of the stress is less than 20 MPa.

2. The diamond crystal according to claim 1, characterized in that, The TTV of the upper surface of the crystal is <10μm, and the TTV of the lower surface is <10μm; The crystal has no cracks or the number of cracks larger than 10 μm in the crystal is 1.

3. A diamond growth and deposition apparatus, characterized in that, include: External molybdenum support assembly: From top to bottom, the external molybdenum support, the outer base, and the outer support column are connected in sequence. The outer base and the outer support column are detachably connected. The center of the external molybdenum support is provided with an opening. Inner molybdenum support assembly: The inner molybdenum support assembly is located at the center of the outer molybdenum support assembly, and is connected from top to bottom to the inner molybdenum support, inner base and inner support column. The inner base and the inner support column are detachably connected. The inner molybdenum support is located in the central opening of the outer molybdenum support, and the outer molybdenum support and the inner molybdenum support are arranged along the same central axis. There is a gap between the inner molybdenum support and the outer molybdenum support. Drive system: The drive system is connected to the inner support column, and the drive system is used to drive the inner support column to lift, rotate and move. The outer support column and the inner support column are equipped with spiral circulating water cooling channels.

4. The diamond growth and deposition apparatus according to claim 3, characterized in that, The diameter of the inner molybdenum holder is the same as the diameter of the seed crystal; and / or The distance between the inner molybdenum support and the outer molybdenum support is 'a', and the value of 'a' ranges from 0.05 to 1.0 mm.

5. The diamond growth and deposition apparatus according to claim 3, characterized in that, The lifting stroke of the drive system is 0.1mm-20mm, and the speed at which the inner bearing column is driven to rotate is 0.1-20rpm.

6. A dynamic height-compensated MPCVD diamond growth method, characterized in that, It is carried out using the diamond growth and deposition apparatus according to any one of claims 3-5, and includes the following steps: (1) Pretreatment: Place the seed crystal on the inner molybdenum support, evacuate the chamber, and then perform in-situ etching and cleaning on the surface of the seed crystal; (2) Growth: In a hydrogen atmosphere, methane, oxygen, nitrogen and argon are introduced in sequence to make the seed crystal grow to a thickness of 0.3-10 mm at a pressure of 5k-30kPa and a temperature of 800-1200℃. During the growth process, the inner molybdenum support is driven to rotate and descend by the drive system, so that the diamond growth surface is not higher than the upper surface of the outer molybdenum support. (3) Annealing: After growth, turn off methane and keep the crystal temperature at 800-1200℃; then turn off nitrogen, oxygen and argon and anneal the crystal at 800-1000℃ for 1-10 hours in a hydrogen atmosphere, cool down and obtain the crystal.

7. The MPCVD diamond growth method with dynamic height compensation according to claim 6, characterized in that, The rotation speed of the inner molybdenum support in step (2) is 0.1-20 rpm; and / or The rate at which the inner molybdenum support descends is 0.1-100 μm / h.

8. The MPCVD diamond growth method with dynamic height compensation according to claim 6, characterized in that, The height difference between the diamond growth surface and the upper surface of the outer molybdenum support in step (2) is d, and the value of d ranges from 0 to 2.0 mm.

9. The MPCVD diamond growth method with dynamic height compensation according to claim 6, characterized in that, The operation of sequentially introducing methane, oxygen, nitrogen, and argon in step (2) is as follows: S1: In a hydrogen atmosphere, introduce methane with a volume fraction of 3-5% for 1-2 hours; S2: Reduce the volume fraction of methane to 1-2%, and introduce oxygen with a volume fraction of 0.1-2% for 5-10 minutes; S3: Introduce nitrogen gas with a volume fraction of 0.1-2% for 5-10 minutes; S4: Finally, introduce argon gas with a volume fraction of 0.1-2%.

10. The MPCVD diamond growth method with dynamic height compensation according to claim 6, characterized in that, In step (2), borane gas or phosphine gas is also introduced.

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