A flow-guiding sample holder and system for MPCVD system

Abstract

The application discloses a gas-guiding sample holder for an MPCVD system, comprising: a sample holder body for being horizontally placed in a reaction cavity, a gas guiding inlet for guiding gas flow being arranged at the upper center of the sample holder body; the lower part of the sample holder body is in a cylindrical shape, and the upper part comprises a flow baffle and a flow guiding table arranged coaxially, the flow baffle is located at the outer side and is in a circular ring body. The flow guiding table is a circular table body with a small upper part and a large lower part; the upper surface of the flow guiding table is horizontal, and is used for placing a diamond sample; the diameter of the lower end of the flow guiding table is the same as the inner ring diameter of the flow baffle, and the height of the flow guiding table satisfies the following condition: when the diamond sample is placed on the flow guiding table, the upper surface of the diamond sample does not exceed the upper surface of the flow baffle. A plurality of radial flow guiding holes are uniformly and periodically arranged around the bottom of the flow baffle. The sample holder provides a stable gas flow environment for diamond growth, and reduces the formation of defects such as polycrystal on the edge of the diamond.

Description

Technical field

[0001] The present invention belongs to the technical field of diamond material growth, and in particular relates to a flow-guiding sample holder and system for an MPCVD system. [Background Technology]

[0002] As we all know, diamond has excellent thermal, electrical, mechanical, optical, and biocompatible properties. For example, it has high thermal conductivity and is an excellent heat sink material. It has a band gap of 5.5eV, a breakdown voltage greater than 10MV / cm, and an electron mobility of 4500cm 2 / Vs, hole mobility is 3800cm 2 / Vs, which gives diamond excellent electrical properties unmatched by other semiconductor materials, making it suitable for the manufacture of ultra-high-frequency and ultra-high-power electronic devices. It is the hardest known natural substance, 1170 and 140 times harder than quartz and corundum, respectively, and is used in cutting. It has high transmittance from the near-ultraviolet to the far-infrared, making it suitable for use as a window material. It is chemically stable, resistant to acid and alkali corrosion, and has no significant rejection reaction with carbon-based organisms, making it a suitable replacement for heart valves. Therefore, diamond has enormous application potential and is gradually becoming a hot topic in scientific research.

[0003] There are many methods for growing diamond, including hot-filament chemical vapor deposition (HFD), high-temperature and high-pressure deposition (HTHP), and microwave plasma chemical vapor deposition (MPCVD). MPCVD is the most widely used method because it produces high-quality diamonds with few impurities. The source gas required for diamond growth (methane, hydrogen, oxygen, nitrogen, etc.) is introduced from above the diamond sample and flows across the diamond surface and sidewalls to achieve diamond growth.

[0004] Diamond growth using MPCVD inevitably requires the use of a sample holder, which is then placed on a sample stage. The material, structure, and dimensions of the sample holder directly impact the quality of diamond growth. Experiments have confirmed that grooved holders are most conducive to diamond growth. However, simulation results show that these grooved holders also have a serious drawback: highly turbulent airflow along the diamond sidewalls. This creates an extremely unstable environment for diamond growth, potentially leading to defects such as polycrystalline diamonds. [Summary of the invention]

[0005] The purpose of the present invention is to provide a flow-guiding sample holder and system for an MPCVD system, which can provide a stable airflow environment for diamond growth and reduce the formation of defects such as diamond edge polycrystalline.

[0006] The present invention adopts the following technical solution: a gas-guided sample holder for an MPCVD system, characterized in that it includes: a sample holder body, which is used to be placed horizontally in a reaction chamber, and a gas inlet for introducing gas flow is provided at the center of the upper part of the sample holder body; the lower part of the sample holder body is cylindrical, and its upper part includes a coaxially arranged baffle and a guide platform, and the baffle is located on the outside and is a circular body.

[0007] The guide table is a truncated cone with a small top and a large bottom. The upper surface of the guide table is horizontal and is used to place diamond samples. The diameter of the lower end of the guide table is the same as the diameter of the inner ring of the baffle. The height of the guide table meets the following conditions: when the diamond sample is placed on the guide table, the upper surface of the diamond sample does not exceed the upper surface of the baffle.

[0008] A plurality of radial guide holes are provided around the bottom of the baffle at regular intervals and evenly throughout the baffle; each guide hole is used to guide the airflow through the gas inlet, the surface of the diamond sample, the side wall of the guide table, and then out of the sample holder body.

[0009] Furthermore, the angle between the side wall of the guide platform and the horizontal plane is α, and the value range of α is 20° to 80°.

[0010] Furthermore, the inner diameter of each guide hole is 1 mm to 10 mm.

[0011] Furthermore, the cylindrical lower portion of the sample holder body, the baffle plate and the flow guide platform are all coaxially arranged integrated structures.

[0012] Furthermore, the guide holes are in one row or multiple rows evenly distributed from top to bottom.

[0013] The present invention also discloses an MPCVD system, comprising the above-mentioned gas-conducting sample holder for the MPCVD system.

[0014] The beneficial effects of the present invention are as follows: the airflow flows downward along the side wall of the guide platform and flows out radially from the guide hole at the bottom. The gas does not form a vortex at the bottom, thereby avoiding the formation of a chaotic airflow environment around the diamond and reducing the formation of defects such as polycrystalline at the edge of the diamond.

Brief Description of the Drawings

[0015] Figure 1 This is a schematic diagram of the conventional sample holder structure;

[0016] Figure 2 This is a schematic diagram of the structure of a flow-guiding sample holder that can be used in an MPCVD system;

[0017] Figure 3 A partial enlarged view of a flow-guided sample holder that can be used in an MPCVD system;

[0018] Figure 4 A top view of a flow-guided sample holder that can be used in an MPCVD system;

[0019] Including: 1. Sample stage; 2. Sample holder body; 3. Guide platform; 4. Guide hole; 5. Diamond sample; 6. Airflow, 7. Baffle, 8. Conventional sample holder. [Specific implementation method]

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

[0021] The present invention discloses a gas-guided sample holder for an MPCVD system, comprising a sample holder body 2 for horizontal placement within a reaction chamber. A gas inlet for introducing a gas flow 6 is provided at the center of the upper portion of the sample holder body 2. The lower portion of the sample holder body 2 is cylindrical, and the upper portion includes a coaxially arranged baffle plate 7 and a flow guide platform 3. The baffle plate 7 is located on the outer side and is an annular shape. The gas flow 6 is a microwave plasma gas flow.

[0022] The above-mentioned guide platform 3 is a truncated cone with a small top and a large bottom; the upper surface of the guide platform 3 is horizontal and is used to place the diamond sample 5; the diameter of the lower end of the guide platform 3 is the same as the diameter of the inner ring of the baffle 7, and the height of the guide platform 3 meets the following conditions: when the diamond sample 5 is placed on the guide platform 3, the upper surface of the diamond sample 5 does not exceed the upper surface of the baffle 7.

[0023] A plurality of radial guide holes 4 are provided around the bottom of the baffle 7 at regular intervals. Each guide hole 4 is used to guide the air flow 6 through the gas inlet, the surface of the diamond sample 5, and the side wall of the guide table 3 and then out of the sample holder body 2.

[0024] The angle between the side wall of the guide platform 3 and the horizontal plane is α, and the value range of α is 20° to 80°.

[0025] The aforementioned guide holes 4 can be circular, square, or have other regular or irregular shapes. Regardless of the shape, the diameter should be small to ensure that the equipotential surface in the electric field above the holes does not fluctuate significantly when the microwave plasma is discharged. When circular, the inner diameter of each guide hole 4 is 1 mm to 10 mm. To ensure rapid gas discharge, the guide holes 4 are arranged in a single row or multiple rows evenly distributed from top to bottom.

[0026] The cylindrical lower portion of the sample holder body 2, the baffle plate 7 and the flow guide platform 3 are all coaxially arranged integral structures.

[0027] The present invention also discloses an MPCVD system, comprising the above-mentioned gas-conducting sample holder for the MPCVD system.

[0028] The present invention also discloses an MPCVD system, including the aforementioned gas-conducting sample holder for use in an MPCVD system. The sample holder is placed horizontally on a sample stage 1, and both are disposed within a reaction chamber, which is a closed space within which a microwave plasma diamond film growth environment is formed.

[0029] A diamond sample 5 is placed in the center of the sample holder body 2. Airflow 6 flows downward from above the diamond sample 5, flows along the sidewalls of the diamond sample 5, and then flows downward along the sidewalls of the guide platform 3. When it reaches the bottom, the flow direction changes and flows out through the radial guide holes 4. This reduces airflow chaos on the diamond sidewalls, provides a stable airflow environment for diamond growth, and reduces the formation of defects such as polycrystalline diamond edges.

[0030] Sample stage 1 is made of a thermally conductive material, such as copper. Copper is chosen because it minimizes temperature transfer. While copper is only an optimal solution, other materials with the same performance can also be used. Sample holder body 2 is made of molybdenum, currently the most effective metal for growing diamonds.

[0031] The diamond growth process is as follows: first, the sample holder is placed on the sample stage 1. Then, the diamond sample 5 is placed on the upper part of the sample holder body 2 and located at the center of the sample holder body 2. Finally, the gas required for diamond growth is introduced downward from above the diamond sample 5, forming an airflow 6 flowing through the surface and side walls of the diamond sample 5 to achieve diamond growth.

[0032] Figure 1 The diagram shows the use of a conventional sample holder to grow diamonds. The conventional sample holder 8 is a columnar body with a groove on the upper wall of the column. The bottom of the groove is horizontal, and the diamond sample 5 is placed horizontally at the bottom of the groove. According to existing simulation results, the airflow flows downward from above the diamond, flows toward the upper wall and circumference of the diamond sample 5, until it reaches the bottom of the cavity. After being blocked by the bottom, the airflow generates vortices, and part of the airflow returns upward and collides with the downward airflow. The airflow in all directions makes the airflow around the diamond very chaotic, which will put the diamond in an unstable growth environment, resulting in defects such as polycrystalline growth at the edge of the diamond.

[0033] The diamond growth process requires a continuous flow of air. The atoms and molecules contained in this airflow are the raw materials for diamond growth. When the airflow is stable, with a consistent direction and velocity, the atoms and molecules will reach the diamond growth surface at a consistent direction and velocity, ensuring that the carbon atoms in the newly grown diamond are arranged in a regular and uniform pattern, guaranteeing that the newly grown diamond is single crystal. However, when the airflow is unstable, such as when vortices form, the atoms or molecules used for diamond growth will reach the diamond growth surface from different directions and velocities. This can easily cause the carbon atoms in the newly grown diamond to have an irregular and non-uniform arrangement, leading to the growth of diamonds with different crystalline phases, known as polycrystalline diamonds. This situation is particularly serious when growing diamonds using unmodified sample holders, especially when a large amount of polycrystals will form at the edges and sides of the sample, seriously affecting the epitaxial growth of single crystal diamonds.

[0034] Using the sample holder of the present invention, the process is as follows Figure 2 、 3 As shown in Figure 4, the bottom of the sample holder is placed horizontally on the sample stage 1, and both are horizontally arranged in the reaction chamber. The microwave plasma gas flow is introduced by the gas inlet. The environment in the reaction chamber meets the conditions for diamond growth. The gas flow is introduced into the upper wall of the diamond sample 5, and downward along the side wall of the diamond sample 5, and continues downward along the side wall of the guide platform 3, and flows radially into the guide holes 4 at the bottom, and is discharged through each guide hole 4. Since the guide platform 3 is a frustum, when the gas flow flows through the side wall of the frustum, it flows down along the side wall, which is equivalent to a buffer and will not form vortices at the bottom. In addition, the gas flow 6 is radially discharged by the guide holes 4, which avoids the gas flow 6 from reversing at the bottom, ensuring that the diamond side wall is in a stable gas flow environment, thereby providing a stable environment for diamond growth and suppressing the formation of defects such as diamond edge polycrystalline.

Claims

1. A gas-conducting sample holder for an MPCVD system, characterized in that: include: The sample holder body (2) is used to be placed horizontally in the reaction chamber, and a gas inlet for introducing an airflow (6) is provided at the center of the upper portion of the sample holder body (2); the lower portion of the sample holder body (2) is cylindrical, and the upper portion thereof includes a coaxially arranged baffle (7) and a flow guide platform (3), wherein the baffle (7) is located on the outside and is an annular body; The guide platform (3) is a truncated cone with a smaller upper portion and a larger lower portion; the upper surface of the guide platform (3) is horizontal and is used to place the diamond sample (5); the diameter of the lower end of the guide platform (3) is the same as the inner ring diameter of the baffle (7); the height of the guide platform (3) satisfies the following conditions: when the diamond sample (5) is placed on the guide platform (3), the upper surface of the diamond sample (5) does not exceed the upper surface of the baffle (7); A plurality of radial flow guide holes (4) are provided at intervals around the bottom of the baffle (7) and are evenly distributed therethrough; each of the flow guide holes (4) is used to guide the air flow (6) through the gas inlet, the surface of the diamond sample (5), the side wall of the flow guide table (3), and then out of the sample holder body (2); The angle between the side wall of the guide platform (3) and the horizontal plane is α, and the value range of α is 20°~80°.

2. The gas-guided sample holder for an MPCVD system according to claim 1, characterized in that: The inner diameter of each of the guide holes (4) is 1 mm to 10 mm.

3. The gas-guided sample holder for an MPCVD system according to claim 2, characterized in that: The cylindrical lower portion of the sample holder body (2), the baffle plate (7) and the flow guide platform (3) are all coaxially arranged integral structures.

4. The gas-guided sample holder for an MPCVD system according to claim 1, characterized in that: The guide holes (4) are arranged in one row or in multiple rows evenly distributed from top to bottom.

5. An MPCVD system, characterized in that: A gas-conducting sample holder for an MPCVD system according to any one of claims 1 to 4.

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