Temperature-adjustable chemical vapor deposition diamond reactor and adjusting method

Abstract

The invention provides a chemical vapor deposition diamond reactor capable of regulating and controlling temperature and a regulation and control method, and the reactor comprises a microwave plasma reactor chamber which is used for coupling microwave energy and exciting plasma; the water cooling table is arranged in the microwave plasma reactor chamber and is used for supporting and cooling a diamond growth base material; the diamond growth base material is arranged on the water cooling table, serves as a carrier for diamond growth and is used for conducting heat between the diamond and the heat transfer gas; and the heat transfer gas discharge gap is positioned between the diamond growth base material and the water cooling table and is used for filling heat transfer gas. According to the method, the comprehensive heat conductivity coefficient of the heat transfer gas is adjusted by introducing the component gases in different proportions, so that the temperature of the diamond is adjusted and controlled, the method has the technical advantages of large temperature adjustable window interval, real-time adjustment and control, accurate adjustment and control, automatic adjustment and control and the like, and the influence of control variables on the growth dynamic process of diamond crystals is avoided; the problems that the diamond temperature is difficult to effectively control and adverse effects are caused by power temperature control are solved.

Description

Technical Field

[0001] The invention relates to the technical field of diamonds, and in particular to a chemical vapor deposition diamond reactor. Background Art

[0002] Diamond has extremely high hardness, ultra-wide bandgap, low dielectric constant, high breakdown voltage, carrier mobility and extremely high thermal conductivity. It has a wide range of applications in the fields of semiconductors, optical windows, heat dissipation materials, electrochemistry and precision machining. Diamond has extremely high thermal conductivity. Growing diamond on a substrate can effectively improve heat dissipation performance, help reduce the operating temperature of the device, improve its performance and stability, and extend its service life. Diamond has good chemical stability and corrosion resistance. In some harsh chemical environments, growing a diamond coating on the surface of the substrate can protect the substrate from chemical corrosion and improve the substrate's resistance to chemical corrosion. By growing diamond films or coatings on ordinary substrates, material costs can be greatly reduced while meeting performance requirements.

[0003] The method of growing diamond on a substrate by chemical vapor deposition (hereafter referred to as CVD) is now well established and widely disclosed in other patents and literature. The manufacture of large-scale and high-quality diamond materials has become possible. Whether CVD diamond is used as a two-dimensional plane (such as optical windows, semiconductor device heat sinks, functional membrane structures, etc.) or a three-dimensional shape (such as dome-shaped aircraft fairings, bulk optical crystal elements, etc.), it can be manufactured in a reasonable manner and used as a reliable and high-performance engineering material in all aspects of the industrial field.

[0004] CVD diamond crystals are usually grown on the substrate surface at a temperature of 700-1200°C. The heat transfer process in the microwave plasma reactor chamber for manufacturing CVD diamond is generally carried out by: microwave heating H 2 With CH 4 The mixed gas with carbon and hydrogen as the main component forms a plasma containing carbon and hydrogen groups. The plasma heats the diamond growth substrate through heat conduction, convection and thermal radiation, so that the substrate reaches the preset growth temperature of diamond. The microwave energy is continuously input and converted into heat energy to continuously heat the substrate. The excess heat of the substrate is extracted from the water cooling stage below. The cooling water temperature of the water cooling stage, the cooling water flow rate and the microwave input energy jointly maintain the growth temperature of diamond.

[0005] Although the above - mentioned scheme has been used until now, an undeniable problem is that the growth of diamond crystals requires a long - term (usually up to dozens of days) and stable temperature environment. The temperature fluctuation usually needs to be controlled within the range of ±10°C. The growth of diamond crystals is accompanied by a dynamic temperature change process. It is usually difficult to accurately match the optimal growth temperature of diamonds through the cooling water temperature and the cooling water flow rate. Although other growth parameters such as microwave input energy and chamber air pressure are easy to adjust dynamically and match the optimal growth temperature, the adjustment of these parameters will affect the kinetic process in the growth of diamond crystals. Summary of the Invention

[0006] In view of the above - mentioned technical problems, the present invention provides a temperature - controllable chemical vapor deposition diamond reactor and a control method, which are used to solve the problem that in the prior art, it is difficult to accurately match the optimal growth temperature of diamonds through the cooling water temperature and the cooling water flow rate in the method of growing diamonds on a substrate by chemical vapor deposition, and the adjustment of other growth parameters will affect the kinetic process in the growth of diamond crystals, resulting in the inconvenience of controlling the diamond temperature. The present invention dynamically and accurately controls the growth temperature of CVD diamond crystals by adjusting the thermal conductivity of the heat - transfer gas medium, so as to overcome the problems existing in the temperature control of the prior art.

[0007] In order to achieve the above - mentioned purpose, the technical solution of the present invention is realized as follows: A temperature - controllable chemical vapor deposition diamond reactor, comprising: A microwave plasma reactor chamber for coupling microwave energy and exciting plasma; A water - cooled table arranged in the microwave plasma reactor chamber for supporting and cooling the diamond growth substrate; A diamond growth substrate arranged on the water - cooled table as a carrier for diamond growth and used for conducting heat between the diamond and the heat - transfer gas; A heat - transfer gas discharge gap located between the diamond growth substrate and the water - cooled table for filling the heat - transfer gas.

[0008] Furthermore, a heat - transfer gas input port leading to the heat - transfer gas discharge gap is provided on the microwave plasma reactor chamber for inputting the heat - transfer gas for regulating the diamond temperature.

[0009] Furthermore, a reaction gas input port is provided on the microwave plasma reactor chamber for inputting the reaction gas participating in the growth of diamond crystals; a gas discharge port is also provided on the microwave plasma reactor chamber for discharging the mixed gas of the reaction gas and the heat - transfer gas.

[0010] Furthermore, it further includes an automatic temperature control system for the diamond temperature, and the automatic temperature control system includes: A temperature measurement device, connected to the chamber of a microwave plasma reactor for real-time acquisition of the diamond temperature and conversion of the temperature into a digital signal; A temperature control module, connected to the temperature measurement device for receiving the digital signal of the temperature measurement device, processing the digital signal and issuing a component gas ratio adjustment instruction; A multi-gas passage, connected to the heat transfer gas input port for conveying each component gas of the heat transfer gas; A gas flow control module, connected to the multi-gas passage for receiving the component gas ratio adjustment instruction and adjusting the ratio of the conveyed component gases according to the instruction to obtain the heat transfer gas with the adjusted thermal conductivity.

[0011] A regulation method for regulating the temperature of chemically vapor-deposited diamond, including the chemically vapor-deposited diamond reactor with adjustable temperature described in any one of the above, and further including the following steps: S1. Introduce a reaction gas for diamond crystal growth into the chamber of the microwave plasma reactor; S2. Input microwave energy into the chamber of the microwave plasma reactor to form a plasma; S3. The plasma provides the temperature for diamond growth for the diamond growth substrate; S4. Introduce a heat transfer gas into the chamber of the microwave plasma reactor. When the diamond temperature is lower than the preset temperature, reduce the thermal conductivity of the heat transfer gas medium; when the diamond temperature is higher than the preset temperature, increase the thermal conductivity of the heat transfer gas medium; S5. The heat transfer gas completes the heat transfer process within the heat transfer gas discharge gap, enters the chamber of the microwave plasma reactor and is discharged through the gas discharge port.

[0012] Further, the heat transfer gas includes hydrogen and / or an inert gas.

[0013] Further, the heat transfer gas is n a mixed gas composed of component gases, n ≥2.

[0014] Further, n among the component gases, there are at least one gas with a thermal conductivity > 0.1 W / (m·K) and at least one gas with a thermal conductivity < 0.1 W / (m·K).

[0015] Further, the method for adjusting the thermal conductivity of the heat transfer gas medium in step S4 is: Mix n component gases at normal temperature and pressure and continuously adjust the ratio of each component gas; by increasing the ratio of the component gas with a higher thermal conductivity, the thermal conductivity of the heat transfer gas medium is increased; by reducing the ratio of the component gas with a higher thermal conductivity, the thermal conductivity of the heat transfer gas medium is reduced.

[0016] Furthermore, it also includes a temperature control method for an automatic temperature control system, which comprises the following steps: A1. The temperature measuring device collects the temperature of the diamond in real time and converts the temperature into a digital signal and transmits it to the temperature control module; A2. The temperature control module processes the digital signal according to the PID algorithm and issues a component gas ratio adjustment instruction to the gas flow control module; A3. The gas flow control module adjusts the component gases transported through multiple gas passages according to the component gas ratio adjustment instruction to obtain a heat transfer gas with adjusted thermal conductivity; A4. The heat transfer gas with adjusted thermal conductivity acts on the diamond growth substrate in the chamber of the microwave plasma reactor to adjust the temperature of the diamond. The adjusted temperature is collected in real time by the temperature measuring device again, forming a closed loop of temperature control.

[0017] Advantages of the present invention: 1. The present invention realizes the control of the diamond temperature by adjusting the thermal conductivity of the heat transfer gas medium, and has technical advantages such as a large temperature controllable window interval, real-time control, a temperature control accuracy within ±1°C, automatic control, etc., and avoids the influence of control variables on the diamond crystal growth kinetic process; 2. When the temperature of the diamond is lower than the preset temperature, the present invention reduces the thermal conductivity of the heat transfer gas medium; when the temperature of the diamond is higher than the preset temperature, the present invention increases the thermal conductivity of the heat transfer gas medium, thereby realizing the real-time and precise control of the diamond temperature, and avoiding the influence of control variables on the diamond growth; 3. The present invention overcomes the problems of the difficult effective control of the diamond temperature and the adverse effects brought by power temperature control. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0019] Figure 1 It is the heat transfer structure of the chamber of the microwave plasma reactor of the present invention; Figure 2 It is the relationship between the thermal conductivity of the mixed gas and the components of the mixed gas of the present invention; Figure 3 It is the automatic temperature control system for the closed-loop control of the diamond temperature of the present invention.

[0020] In the figure: 1. Microwave plasma reactor chamber; 2. Plasma; 3. Reaction gas inlet; 4. Heat transfer gas inlet; 5. Diamond growth substrate; 6. Heat transfer gas discharge gap; 7. Water-cooled table; 8. Gas outlet. Detailed implementation mode

[0021] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0022] A chemically vapor deposited diamond reactor with adjustable temperature according to the present invention, as Figure 1 shown, includes: a microwave plasma reactor chamber 1 for coupling microwave energy and exciting plasma; a water-cooled table 7 is arranged inside the microwave plasma reactor chamber 1 for supporting and cooling the diamond growth substrate 5; a diamond growth substrate 5 is arranged on the water-cooled table 7. The diamond growth substrate 5 serves as a carrier for diamond growth and is used for conducting heat between the diamond and the heat transfer gas; there is a heat transfer gas discharge gap 6 between the diamond growth substrate 5 and the water-cooled table 7 for filling the heat transfer gas.

[0023] Furthermore, as Figure 1 shown, the microwave plasma reactor chamber 1 is provided with a heat transfer gas inlet 4 leading to the heat transfer gas discharge gap 6 for inputting the heat transfer gas for regulating the temperature of the diamond. The microwave plasma reactor chamber 1 is provided with a reaction gas inlet 3 for inputting the reaction gas participating in the growth of diamond crystals; the microwave plasma reactor chamber 1 is also provided with a gas outlet 8 for discharging the mixture of the reaction gas and the heat transfer gas.

[0024] In a preferred embodiment, the chemically vapor deposited diamond reactor further includes an automatic temperature control system for the diamond temperature. The automatic temperature control system includes a temperature measuring device, a temperature control module, a multi-gas path, and a gas flow control module. The temperature measuring device is connected to the inside of the microwave plasma reactor chamber 1 for real-time collection of the diamond temperature and conversion of the temperature into a digital signal; the temperature control module is connected to the temperature measuring device for receiving the digital signal of the temperature measuring device, processing the digital signal, and issuing a component gas ratio adjustment instruction; the multi-gas path communicates with the heat transfer gas inlet 4 for conveying each component gas of the heat transfer gas into the heat transfer gas discharge gap 6; the gas flow control module is connected to the multi-gas path for receiving the component gas ratio adjustment instruction and adjusting the ratio of the conveyed component gases according to the instruction to obtain the heat transfer gas with adjusted thermal conductivity.

[0025] In another preferred embodiment, a method for regulating the temperature of chemical vapor deposition diamond includes the temperature-adjustable chemical vapor deposition diamond reactor described in any one of the above, and further includes the following steps: S1. Introduce reaction gas mainly composed of H 2 and CH 4 into the chamber 1 of the microwave plasma reactor through the reaction gas inlet 3 for diamond crystal growth; S2. Input microwave energy into the chamber 1 of the microwave plasma reactor. Under the confinement of the reactor chamber, a strong electric field region is formed above the diamond growth substrate, and the strong electric field excites the reaction gas to form plasma 2; S3. Plasma 2 provides the active substance components containing carbon and hydrogen groups necessary for diamond growth for the diamond growth substrate 5, and at the same time provides the temperature necessary for diamond growth for the substrate; S4. Introduce heat transfer gas into the chamber 1 of the microwave plasma reactor through the heat transfer gas inlet 4. The heat transfer gas fills the heat transfer gas discharge gap 6. When the actual temperature of the diamond is lower than the preset temperature of the diamond, adjust and reduce the thermal conductivity of the heat transfer gas medium. The heat transfer gas medium reduces the heat transfer from the diamond growth substrate 5 to the water-cooled table 7, the temperature of the diamond growth substrate increases, and the temperature of the diamond increases; when the temperature of the diamond is higher than the preset temperature of the diamond, adjust and increase the thermal conductivity of the heat transfer gas medium. The heat transfer gas medium increases the heat transfer from the diamond growth substrate 5 to the water-cooled table 7, the temperature of the diamond growth substrate decreases, and the temperature of the diamond decreases; S5. The heat transfer gas completes the heat transfer process in the heat transfer gas discharge gap 6 at the bottom of the diamond growth substrate 5, enters the chamber 1 of the microwave plasma reactor from the heat transfer gas discharge gap 6, and is discharged through the gas outlet 8.

[0026] Among them, the heat transfer gas is a gas that does not have a significant impact on the chemical vapor deposition reaction process of diamond, and the heat transfer gas includes hydrogen and / or inert gas. In this embodiment, the heat transfer gas is a mixed gas composed of at least two of hydrogen and inert gas. That is to say, the heat transfer gas is a mixed gas composed of n component gases, n ≥2.

[0027] Furthermore, n among the component gases, there is at least one gas with a thermal conductivity > 0.1 W / (m·K) and at least one gas with a thermal conductivity < 0.1 W / (m·K).

[0028] Since the heat conduction of a gas is a process in which heat is transferred through the internal molecular or atomic collisions when the gas is heated. The molecules or atoms in the high-temperature region have a higher average kinetic energy. They collide with the surrounding molecules or atoms and transfer the thermal energy in the form of kinetic energy, causing the heat to propagate in the gas until the entire system reaches thermal equilibrium. The thermal conductivity of a gas is an important physical parameter to measure the heat conduction performance of the gas. The thermal conductivity depends on factors such as the type of gas, temperature, pressure, etc. Under normal temperature and pressure conditions, the thermal conductivity of a mixed gas is calculated by the following formula: λ in =Σ λ i y i M i 1 / 3 / Σ y i M i 1 / 3 In the formula: λ in — At normal temperature and pressure n each i thermal conductivity of the component gas (mixed gas); λ i — At normal temperature and pressure i thermal conductivity of the component gas; M i — i molecular weight of the component gas; y i — In the mixed gas i mole fraction of the component gas.

[0029] It can be obtained from the formula that under certain temperature and pressure conditions, by adjusting the composition and content of each component gas in the mixed gas, the thermal conductivity of the mixed gas can be changed.

[0030] Therefore, in the present invention, through the mixing design of the composition of the heat transfer gas introduced into the bottom of the diamond growth substrate, the content of the mixed gas components is adjusted to change the thermal conductivity of the heat transfer gas.

[0031] Furthermore, the heat conduction performance of a gas is usually poorer than that of solids and liquids. The thermal conductivity of common gases is usually in the range of 0.01 W / (m·K) to 0.2 W / (m·K). Table 1 lists the thermal conductivities of some common gases under normal temperature and pressure.

[0032] Table 1 Thermal Conductivities of Some Common Gases under Normal Temperature and Pressure Serial number Gas composition Thermal conductivity W / (m·K) 1 <![CDATA[H 2 > 0.168 2 He 0.151 3 <![CDATA[N 2 > 0.026 4 <![CDATA[O 2 > 0.024 5 Ne 0.046 6 Ar 0.018 7 Kr 0.009 8 Xe 0.005 9 CO 0.023 10 <![CDATA[CO 2 > 0.016 11 <![CDATA[CH 4 > 0.032 12 Air 0.026 Furthermore, at normal temperature and pressure, two or more gases are combined, and the gas composition is changed between 0 mol.% and 100 mol.%, obtaining the relationship between the thermal conductivity of the mixed gas with non-linear change and the components of the mixed gas. As Figure 2 shown, when component gases with high thermal conductivity (>0.1 W / (m·K)) and component gases with low thermal conductivity (<0.1 W / (m·K)) are mixed, a relatively large adjustable range of thermal conductivity can be obtained; when component gases with high thermal conductivity (>0.1 W / (m·K)) are mixed or component gases with low thermal conductivity (<0.1 W / (m·K)) are mixed, a relatively small adjustable range of thermal conductivity can be obtained.

[0033] Therefore, the method for adjusting the thermal conductivity of the heat transfer gas medium in step S4 is as follows: Mix n component gases at normal temperature and pressure, and continuously adjust the proportion of each component gas; by increasing the proportion of the component gas with higher thermal conductivity, the thermal conductivity of the heat transfer gas medium is increased; by decreasing the proportion of the component gas with higher thermal conductivity, the thermal conductivity of the heat transfer gas medium is decreased.

[0034] Furthermore, the method for controlling the temperature of chemical vapor deposition diamond also includes the temperature control method of an automatic temperature control system, including the following steps: A1. The temperature measuring device real-time collects the diamond temperature, and converts the temperature into a digital signal and transmits it to the temperature control module; A2. The temperature control module processes the digital signal according to the PID algorithm, and issues a component gas proportion adjustment instruction to the gas flow control module; A3. The gas flow control module adjusts the proportion of the component gases transported through multiple gas paths according to the component gas proportion adjustment instruction, obtaining the heat transfer gas with adjusted thermal conductivity; A4. The heat transfer gas with adjusted thermal conductivity acts on the diamond growth substrate 5 in the microwave plasma reactor chamber 1 to adjust the diamond temperature, and the adjusted temperature is again real-time collected by the temperature measuring device, forming a closed loop of temperature control.

[0035] Example 1 In the microwave plasma reactor chamber 1, reaction gases mainly composed of H 2 and CH 4 are introduced for diamond crystal growth.

[0036] Microwave energy is input into the microwave plasma reactor chamber 1. Under the confinement of the reactor chamber, a strong electric field region is formed above the diamond growth substrate 5, and the strong electric field excites the reaction gases to form plasma 2.

[0037] The plasma 2 provides the active substance components containing carbon and hydrogen groups necessary for diamond growth to the diamond growth substrate 5, and at the same time provides the temperature necessary for diamond growth to the substrate.

[0038] The temperature measuring device collects the diamond temperature in real time, converts the temperature into a digital signal and transmits it to the temperature control module. The temperature control module receives the digital signal from the temperature measuring device, processes the digital signal according to the PID algorithm, and issues a component gas ratio adjustment instruction to the gas flow control module.

[0039] The gas flow control module receives the component gas ratio adjustment instruction, and mixes the He gas and Ar gas component gases transported through multiple gas paths at room temperature and atmospheric pressure according to the instruction with a mass flow ratio of 2:1 to obtain a heat transfer gas with adjusted thermal conductivity. The preset temperature is 1020 °C, 100 sccm of He gas and 50.0 sccm of Ar gas are introduced.

[0040] When the actual diamond temperature is 1010 °C, which is lower than the preset diamond temperature, the He gas flow is reduced to 85 sccm and the Ar gas flow is increased to 65.2 sccm to reduce the thermal conductivity of the heat transfer gas medium. The heat transfer gas medium reduces the heat transfer from the diamond growth substrate 5 to the water-cooled table 7, the temperature of the diamond growth substrate increases, and the diamond temperature increases.

[0041] When the diamond temperature is 1036 °C, which is higher than the preset diamond temperature, the He gas flow is increased to 115 sccm and the Ar gas flow is reduced to 35.3 sccm to increase the thermal conductivity of the heat transfer gas medium. The heat transfer gas medium increases the heat transfer from the diamond growth substrate 5 to the water-cooled table 7, the temperature of the diamond growth substrate decreases, and the diamond temperature decreases.

[0042] The adjusted temperature is collected by the temperature measuring device in real time, converted into a digital signal, and transmitted to the temperature control module again to form a closed loop of temperature control. Finally, the temperature is stabilized at 1020 ± 1 °C.

[0043] The heat transfer gas completes the heat transfer process at the bottom of the diamond growth substrate, enters the reactor chamber from the heat transfer gas discharge gap, and is discharged from the gas outlet, thus completing the temperature adjustment process.

[0044] Example 2 In the microwave plasma reactor chamber 1, a reaction gas mainly composed of H 2 and CH 4 is introduced for diamond crystal growth.

[0045] Microwave energy is input into the microwave plasma reactor chamber 1. Under the confinement of the reactor chamber, a strong electric field region is formed above the diamond growth substrate, and the strong electric field excites the reaction gas to form plasma 2.

[0046] The plasma 2 provides the active substance components containing carbon and hydrogen groups necessary for diamond growth to the diamond growth substrate 5, and at the same time provides the temperature necessary for diamond growth to the substrate.

[0047] The temperature measurement device collects the diamond temperature in real time, converts the temperature into a digital signal and transmits it to the temperature control module. The temperature control module receives the digital signal from the temperature measurement device, processes the digital signal according to the PID algorithm, and issues a component gas ratio adjustment instruction to the gas flow control module.

[0048] The gas flow control module receives the component gas ratio adjustment instruction, and mixes the H 2 gas and Ar gas component gases transported through multiple gas paths at a mass flow ratio of 2:1 according to the instruction at normal temperature and pressure to obtain the heat transfer gas with adjusted thermal conductivity. The preset temperature is 800 °C, and 100 sccm of H 2 gas and 50.0 sccm of Ar gas are introduced.

[0049] When the actual diamond temperature is 798 °C, which is lower than the preset diamond temperature, the flow rate of H 2 gas remains unchanged at 100 sccm and the flow rate of Ar gas is increased to 51.6 sccm to reduce the thermal conductivity of the heat transfer gas medium. The heat transfer gas medium reduces the heat transfer from the diamond growth substrate to the water-cooled table, the temperature of the diamond growth substrate rises, and the diamond temperature rises.

[0050] When the diamond temperature is 803 °C, which is higher than the preset diamond temperature, the flow rate of H 2 gas remains unchanged at 100 sccm and the flow rate of Ar gas is reduced to 48.5 sccm to increase the thermal conductivity of the heat transfer gas medium. The heat transfer gas medium increases the heat transfer from the diamond growth substrate to the water-cooled table, the temperature of the diamond growth substrate decreases, and the diamond temperature decreases.

[0051] The adjusted temperature is collected by the temperature measurement device in real time, converted into a digital signal, and transmitted to the temperature control module again to form a closed loop of temperature control. Finally, the temperature is stabilized at 800 ± 1 °C.

[0052] The heat transfer gas completes the heat transfer process at the bottom of the diamond growth substrate, enters the reactor chamber from the heat transfer gas discharge gap, and is discharged from the gas outlet, thereby completing the temperature adjustment process.

[0053] Example 3 In the reactor chamber, a reaction gas mainly composed of H 2 and CH 4 is introduced for diamond crystal growth.

[0054] Microwave energy is input into the reactor chamber. Under the confinement of the reactor chamber, a strong electric field region is formed above the diamond growth substrate, and the strong electric field excites the reaction gas to form a plasma.

[0055] The plasma provides the active substance components containing carbon and hydrogen groups necessary for diamond growth for the diamond growth substrate 5, and at the same time provides the necessary temperature for the substrate for diamond growth.

[0056] The temperature measurement device collects the diamond temperature in real time, converts the temperature into a digital signal and transmits it to the temperature control module. The temperature control module receives the digital signal from the temperature measurement device, processes the digital signal according to the PID algorithm, and issues a component gas ratio adjustment instruction to the gas flow control module.

[0057] The gas flow control module receives the component gas ratio adjustment instruction, and mixes the He gas and Ne gas component gases transported through multiple gas paths at room temperature and normal pressure according to the instruction with a mass flow ratio of 2:1 to obtain a heat transfer gas with adjusted thermal conductivity. The preset temperature is 930 °C, 100 sccm of He gas and 50.0 sccm of Ne gas are introduced.

[0058] When the actual temperature of the diamond is 905 °C, which is lower than the preset temperature of the diamond, the He gas flow is reduced to 94 sccm and the Ne gas flow remains unchanged at 50.0 sccm to reduce the thermal conductivity of the heat transfer gas medium. The heat transfer gas medium reduces the heat transfer from the diamond growth substrate to the water-cooled table, the temperature of the diamond growth substrate increases, and the diamond temperature increases.

[0059] When the diamond temperature is 935 °C, which is higher than the preset temperature of the diamond, the He gas flow is increased to 112 sccm and the Ne gas flow remains unchanged at 50.0 sccm to increase the thermal conductivity of the heat transfer gas medium. The heat transfer gas medium increases the heat transfer from the diamond growth substrate to the water-cooled table, the temperature of the diamond growth substrate decreases, and the diamond temperature decreases.

[0060] The adjusted temperature is collected by the temperature measurement device in real time, converted into a digital signal, and transmitted to the temperature control module again to form a closed loop of temperature control, and finally the temperature is stabilized at 930 ± 1 °C.

[0061] The heat transfer gas completes the heat transfer process at the bottom of the diamond growth substrate, enters the reactor chamber from the heat transfer gas discharge gap, and is discharged from the gas outlet, thereby completing the temperature adjustment process.

[0062] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: within the spirit and principle of the present invention, any modification to the technical solutions recorded in the foregoing embodiments, or any equivalent replacement of some or all of the technical features, and such modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the various embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A temperature-adjustable chemical vapor deposition diamond reactor, characterized in that: include: A microwave plasma reactor chamber (1) for coupling microwave energy and exciting plasma; A water cooling stage (7) is arranged in the microwave plasma reactor chamber (1) and is used to support and cool the diamond growth substrate (5); A diamond growth substrate (5) is arranged on a water cooling platform (7) as a carrier for diamond growth and used for conducting heat between the diamond and the heat transfer gas; The heat transfer gas exhaust gap (6) is located between the diamond growth substrate (5) and the water cooling stage (7) and is used for filling the heat transfer gas.

2. The temperature-adjustable chemical vapor deposition diamond reactor according to claim 1, characterized in that: The microwave plasma reactor chamber (1) is provided with a heat transfer gas input port (4) leading to a heat transfer gas discharge gap (6) for inputting heat transfer gas for regulating the temperature of the diamond.

3. The temperature-adjustable chemical vapor deposition diamond reactor according to claim 2, characterized in that: The microwave plasma reactor chamber (1) is provided with a reaction gas input port (3) for inputting reaction gas involved in the growth of diamond crystals; the microwave plasma reactor chamber (1) is also provided with a gas discharge port (8) for discharging a mixture of reaction gas and heat transfer gas.

4. The temperature-adjustable chemical vapor deposition diamond reactor according to claim 2 or 3, characterized in that: It also includes an automatic temperature control system for diamond temperature, the automatic temperature control system comprising: A temperature measuring device connected to the microwave plasma reactor chamber (1) for collecting diamond temperature in real time and converting the temperature into a digital signal; A temperature control module, connected to the temperature measuring device, for receiving a digital signal from the temperature measuring device, processing the digital signal and issuing a component gas ratio adjustment instruction; A plurality of gas passages connected to the heat transfer gas input port (4) for conveying various component gases of the heat transfer gas; The gas flow control module is connected to the multiple gas passages to receive component gas ratio adjustment instructions, and proportionally adjusts the delivered component gases according to the instructions to obtain heat transfer gas with adjusted thermal conductivity.

5. A method for controlling the temperature of chemical vapor deposition diamond, characterized in that: The temperature-adjustable chemical vapor deposition diamond reactor according to any one of claims 1 to 4 further comprises the following steps: S1, introducing a reaction gas for growing diamond crystals into a microwave plasma reactor chamber (1); S2, inputting microwave energy into the microwave plasma reactor chamber (1) to form plasma (2); S3, the plasma (2) provides a temperature for diamond growth for the diamond growth substrate (5); S4, introducing a heat transfer gas into the microwave plasma reactor chamber (1), and when the diamond temperature is lower than a preset temperature, reducing the thermal conductivity of the heat transfer gas medium; when the diamond temperature is higher than the preset temperature, increasing the thermal conductivity of the heat transfer gas medium; S5. The heat transfer gas completes the heat transfer process in the heat transfer gas discharge gap (6), enters the microwave plasma reactor chamber (1), and is discharged through the gas discharge port (8).

6. The method for controlling the temperature of chemical vapor deposition diamond according to claim 5, characterized in that: The heat transfer gas includes hydrogen and / or an inert gas.

7. The method for controlling the temperature of chemical vapor deposition diamond according to claim 6, characterized in that: The heat transfer gas is n A gas mixture consisting of 1 component gas. n ≥2.

8. The method for controlling the temperature of chemical vapor deposition diamond according to claim 7, characterized in that: n The component gases include at least one gas with a thermal conductivity greater than 0.1 W / (m·K) and at least one gas with a thermal conductivity less than 0.1 W / (m·K).

9. The temperature-adjustable chemical vapor deposition diamond reactor and the control method according to claim 8, characterized in that: The method for adjusting the thermal conductivity of the heat transfer gas medium in step S4 is: Will n The gas components are mixed at normal temperature and pressure, and the ratio of each gas component is continuously adjusted; By increasing the proportion of the component gas with higher thermal conductivity, the thermal conductivity of the medium of the heat transfer gas is increased; by reducing the proportion of the component gas with higher thermal conductivity, the thermal conductivity of the medium of the heat transfer gas is reduced.

10. The method for controlling the temperature of chemical vapor deposition diamond according to claim 9, characterized in that: Also included is a temperature control method of an automatic temperature control system, comprising the following steps: A1. The temperature measuring device collects the diamond temperature in real time and converts the temperature into a digital signal to be transmitted to the temperature control module; A2. The temperature control module processes the digital signal according to the PID algorithm and sends a component gas ratio adjustment instruction to the gas flow control module; A3, the gas flow control module proportionally adjusts the component gases transported by the multiple gas passages according to the instructions to obtain the heat transfer gas with adjusted thermal conductivity; A4. The heat transfer gas after the thermal conductivity is adjusted acts on the diamond growth substrate (5) in the microwave plasma reactor chamber (1) to adjust the temperature of the diamond. The adjusted temperature is again collected in real time by the temperature measuring device to form a closed loop of temperature control.

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