Design method of low-power microwave cavity plasma reactor
By designing a low-power microwave cavity plasma reactor suitable for 2.45GHz and 915MHz, the problems of complexity, high cost and low energy utilization of high-power MPCVD equipment are solved, and the effects of simple structure, low cost and low processing difficulty are achieved, with good application prospects and popularization.
Patent Information
- Application Number
- CN202510287697.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-12
- Publication Date
- 2025-06-27
AI Technical Summary
The existing high-power MPCVD equipment has problems such as equipment complexity, high cost, low energy utilization, uneven deposition film quality and high operating energy consumption, which limits its promotion in small and medium-sized applications.
A low-power microwave cavity plasma reactor is designed, using a cylindrical cavity with a simple structure, suitable for 2.45GHz and 915MHz microwaves, including coaxial antenna, coupling cavity, ion chamber, deposition platform and quartz partition. The microwave mode is TEM coupled through coaxial antenna.
It realizes the use of low-power microwave excitation to obtain a larger area of plasma discharge, reduces the difficulty and cost of equipment manufacturing, improves energy efficiency, and obtains higher application prospects and popularization.
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Figure CN120210787A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of microwave plasma chemical vapor deposition thin films, and relates to a design method for a low-power microwave cavity plasma reactor. Background Art
[0002] Microwave plasma chemical vapor deposition (MPCVD) technology couples microwave power into a specific metal enclosed cavity. When the gas in the cavity is within a specific pressure range and the microwave power reaches a certain power density, the gas in the cavity will be ionized to form a plasma region, which can be used for various applications such as chemical vapor deposition and material processing. The MPCVD method has advantages such as high purity and uniform growth in the preparation of diamond thin films.
[0003] In recent years, China has made progress in high-power MPCVD technology, but there is still a certain gap compared with the international advanced level in terms of overall equipment level and industrial application. High-power MPCVD has become an important technology for preparing large-area and high-quality diamond films due to its high-density plasma, good controllability and cleanliness. However, the development of domestic high-power MPCVD equipment lags behind, and there are still certain obstacles. For example, the complexity and high cost of the equipment require complex vacuum systems, cooling systems and high-precision microwave sources, resulting in high equipment costs and limiting its promotion in small and medium-scale applications; under high-power conditions, the coupling efficiency between microwaves and plasma may decrease, resulting in low energy utilization efficiency; the uniformity of high-power plasma is difficult to control, which may lead to uneven quality of the deposited film; the operation energy consumption of high-power MPCVD devices is relatively high, increasing the production cost.
[0004] In the context of the many challenges faced by high-power MPCVD devices, designing an MPCVD device with a simple structure that can achieve large-area discharge deposition at low power has significant application prospects, which can reduce the manufacturing difficulty and cost, obtain higher energy efficiency, and have a wider and more easily promoted market. Summary of the Invention
[0005] Technical Problem: In view of the above technical background, the present invention proposes a low-power microwave cavity plasma reactor, which uses a cylindrical cavity with a simple structure, and the design method is applicable to both 2.45 GHz and 915 MHz. The present invention aims to provide a reactor design method in the MPCVD field that is simple in structure, easy to manufacture and easy to promote.
[0006] Technical solution: To achieve the above object, a low-power microwave cavity plasma reactor of the present invention includes a coaxial antenna, a coupling cavity, an ion chamber, a deposition stage, and a port for applying coaxial TEM wave excitation; wherein, the coupling cavity and the ion chamber form a total cavity, the total cavity is a cylindrical metal cavity, a quartz partition is horizontally placed in the cavity, dividing the total cavity into an upper coupling cavity and a lower ion chamber, the deposition stage is located in the ion chamber, the coaxial antenna is located in the upper part of the coupling cavity, the port for applying coaxial TEM wave excitation is located on the coaxial antenna, the microwave coupling method is coaxial antenna coupling, and the microwave mode is TEM; the reactor is applicable to 915 MHz and 2.45 GHz microwaves.
[0007] The diameter Wc of the total cavity is 2λ, and the height Hc is 3λ, where λ is the microwave wavelength;
[0008] For 915 MHz microwave, Wc is taken as 655.74 mm, and Hc is taken as 983.61 mm; for 2.45 GHz microwave, Wc is taken as 244.90 mm, and Hc is taken as 367.35 mm.
[0009] The thickness h of the quartz partition is taken as 7 mm, and the distance Hg from the bottom of the quartz partition to the bottom of the total cavity is 1.5λ.
[0010] For 915 MHz microwave, Hg is taken as 491.81 mm; for 2.45 GHz microwave, Hg is taken as 183.68 mm.
[0011] The total height of the deposition stage is λ, and it is composed of a bottom column, a base platform, and a raised platform; for 915 MHz microwave, the diameter Ws of the bottom column is taken as 80 mm, and the height Hs is taken as 283.87 mm; the diameter Wu of the base platform is taken as 240 mm, and the height Hu is taken as 40 mm; the diameter of the raised platform is taken as 160 mm, and the height is taken as 4 mm; for 2.45 GHz microwave, the diameter Ws of the bottom column is taken as 40 mm, and the height Hs is taken as 100.45 mm, the diameter Wu of the base platform is taken as 120 mm, and the height Hu is taken as 20 mm, the diameter Wp of the raised platform is taken as 80 mm, and the height Hp is taken as 2 mm.
[0012] For the coaxial antenna, for 915 MHz microwave, the inner diameter R1 is taken as 40 mm, the outer diameter R2 is taken as 200 mm, the outer height H1 is taken as 0.5λ, i.e., 163.94 mm, and the inner height H2 is taken as λ, i.e., 327.87 mm; for 2.45 GHz microwave, the inner diameter R1 is taken as 20 mm, the outer diameter R2 is taken as 100 mm, the outer height H1 is taken as 0.5λ, i.e., 61.23 mm, and the inner height H2 is taken as λ, i.e., 122.45 mm.
[0013] For the selected microwave excitation power, the reaction gas and reaction gas pressure in the ion chamber are set accordingly. The reaction gas can be selected as hydrogen to excite and maintain hydrogen plasma, or hydrogen and methane can be selected to achieve diamond film deposition.
[0014] For 915MHz microwaves, the reaction gas is hydrogen, the power is 5kW, and the gas pressure in the ion chamber should be maintained at 8-10kPa; for 2.45GHz microwaves, the reaction gas is hydrogen, the power is 2kW, and the gas pressure in the ion chamber should be maintained at 15-17kPa.
[0015] Beneficial effects: The present invention proposes a design method for a low-power microwave cavity plasma reactor, the reactor comprising a main cavity, a quartz partition, a deposition platform and a coaxial antenna. The main cavity is a cylindrical metal cavity, the quartz partition is placed horizontally in the cavity, and the main cavity is divided into an upper coupling cavity and a lower ion chamber, the deposition platform is located in the ion chamber, the coaxial antenna is connected to the coupling cavity, the microwave coupling method is coaxial antenna coupling, and the microwave mode is TEM. This design method can be used for 915MHz and 2.45GHz. The advantages of the present invention are: a relatively considerable plasma discharge diameter can be obtained by using low-power microwave excitation, avoiding the potential obstacles in the design, development and use of high-power MPCVD equipment; at the same time, the structure used is very simple, so that the production cost and processing difficulty will be greatly reduced, it has the advantages of simple structure, low cost, low processing difficulty, and has good application prospects and scalability. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 A schematic diagram of the structure of a low-power microwave cavity plasma reactor provided by the present invention; wherein: a coaxial antenna 1, a coupling cavity 2, an ion chamber 3, a deposition platform 4, a port 5 for applying coaxial TEM wave excitation, a quartz partition 6; a bottom column 41, a base 42, and a raised platform 43;
[0017] Figure 2 A diagram illustrating the structure and dimensions of a low-power microwave cavity plasma reactor provided by the present invention;
[0018] Figure 3 The steady-state electron density diagram of the reactor provided by the present invention at 915 MHz, 5 kW, and 8 kPa;
[0019] Figure 4 The steady-state electric field distribution diagram of the reactor provided by the present invention at 915MHz, 5kW, and 8kPa;
[0020] Figure 5 The electron density diagram of the reactor provided by the present invention when the gas pressure is reduced to 5 kPa at 915 MHz and 5 kW;
[0021] Figure 6 The electron density diagram of the reactor provided by the present invention when the gas pressure is increased to 14 kPa at 915 MHz and 5 kW;
[0022] Figure 7Steady-state electron density map of the reactor provided by the present invention at 2.45 GHz, 2 kW, and 15 kPa;
[0023] Figure 8 Steady-state electric field distribution map of the reactor provided by the present invention at 2.45 GHz, 2 kW, and 15 kPa;
[0024] Figure 9 Electron density map of the reactor provided by the present invention at 2.45 GHz and 2 kW when the air pressure is reduced to 13 kPa;
[0025] Figure 10 Electron density map of the reactor provided by the present invention at 2.45 GHz and 2 kW when the air pressure is increased to 21 kPa; Detailed implementation mode
[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments.
[0027] Embodiment 1:
[0028] As Figure 1 shown, the reactor includes a total cavity, a quartz partition, a deposition table, and a coaxial antenna. Figure 1 There is a coaxial antenna 1, a coupling cavity 2, an ion chamber 3, a deposition table 4, a port 5 for applying coaxial TEM wave excitation, and a quartz partition 6.
[0029] According to the design method provided by the present invention, the diameter and height of the total cavity, the shape and position of the quartz partition, the shape and position of the deposition table, and the shape and position of the antenna extending into the cavity are set. For the selected microwave excitation power, the reaction gas and reaction air pressure in the ion chamber should be set accordingly. The reaction gas can be hydrogen to excite and maintain hydrogen plasma, or hydrogen and methane can be used to achieve diamond film deposition.
[0030] Using 915 MHz microwave excitation and selecting hydrogen as the reaction gas to observe the steady-state electron density distribution and electric field distribution, but hydrogen and methane can also be used to simulate diamond film deposition. Through COMSOL Multiphysics simulation and comparison, when 5 kW is selected as the microwave power and the gas pressure in the ion chamber is maintained at 8 - 10 kPa, better observation results will be obtained, but other powers and corresponding gas pressure ranges can also be selected.
[0031] The specific parameter dimensions are as Figure 2 shown. It should be noted that Figure 2It is only a schematic diagram of the parameter design method and not the design drawing of the reaction device. Other details should be added to the drawing. The total cavity is a cylindrical metal cavity. The diameter Wc of the total cavity is 2λ, and the height Hc is 3λ. That is, for 915 MHz microwaves, Wc is taken as 655.74 mm and Hc is taken as 983.61 mm, where λ is the microwave wavelength; the quartz partition is horizontally placed in the cavity, dividing the total cavity into the upper coupling cavity and the lower ion chamber. The thickness h of the quartz partition is taken as 7 mm, and the distance Hg from the bottom of the quartz partition to the bottom of the total cavity is 1.5λ. That is, for 915 MHz microwaves, Hg is taken as 491.81 mm; the deposition stage is located in the ion chamber. The total height of the deposition stage is λ and it consists of a bottom column, a base platform, and a raised platform. For 915 MHz microwaves, the diameter Ws of the bottom column is taken as 80 mm, the height Hs is taken as 283.87 mm, the diameter Wu of the base platform is taken as 240 mm, the height Hu is taken as 40 mm, the diameter of the raised platform is taken as 160 mm, and the height is taken as 4 mm; the coaxial antenna is connected to the coupling cavity. The microwave coupling method is coaxial antenna coupling, and the microwave mode is TEM. For 915 MHz microwaves, the inner diameter R1 is taken as 40 mm, the outer diameter R2 is taken as 200 mm, the outer height H1 is taken as 0.5λ, that is, 163.94 mm, and the inner height H2 is taken as λ, that is, 327.87 mm;
[0032] As Figure 3 shown, under the conditions of 915 MHz, 5 kW, and 8 kPa, the maximum electron density is 9.65×10 16 / m 3 . If the electron density drop to of the maximum value is taken as the boundary of the discharge region, then the diameter of the discharge region is about 98.0 mm. As Figure 4 shown, under the conditions of 915 MHz, 5 kW, and 8 kPa, at steady state, the strong electric field is concentrated on the surface of the deposition stage, and the maximum value is 1.93×10 4 V / m.
[0033] On the premise of 915 MHz and 5 kW, the air pressure in the ion chamber should be maintained at 8 - 10 kPa. When the air pressure is lower than this range, the phenomenon of secondary plasma is likely to occur at the bottom of the quartz partition. As Figure 5 shown, when the air pressure in the ion chamber is 5 kPa, serious secondary plasma appears; when the air pressure is higher than this range, the plasma discharge region shrinks significantly with the increase of air pressure. As Figure 6 shown, when the air pressure in the ion chamber is 14 kPa, the high electron density range shrinks significantly, and the discharge region is about 72.6 mm.
[0034] Example 2:
[0035] Using 2.45 GHz microwave excitation and selecting hydrogen as the reaction gas to observe the electron density distribution and electric field distribution at steady state. However, hydrogen and methane can also be selected to simulate diamond film deposition. After COMSOL Multiphysics simulation and comparison, when selecting 2 kW as the microwave power and maintaining the gas pressure in the ion chamber at 15 - 17 kPa, better observation results will be obtained. However, other powers and corresponding gas pressure ranges can also be selected.
[0036] The specific parameter dimensions are as Figure 2 shown. It should be noted that Figure 2 This is only a schematic diagram of the parameter design method and not the design drawing of the reaction device. Other details should be added to the drawing. The total cavity is a cylindrical metal cavity. The diameter Wc of the total cavity is 2λ, and the height Hc is 3λ. For 2.45 GHz microwave, Wc is taken as 244.90 mm and Hc is taken as 367.35 mm, where λ is the microwave wavelength; the quartz partition is placed horizontally in the cavity, dividing the total cavity into the upper coupling cavity and the lower ion chamber. The thickness h of the quartz partition is taken as 7 mm, and the distance Hg from the bottom of the quartz partition to the bottom of the total cavity is 1.5λ. For 2.45 GHz microwave, Hg is taken as 183.68 mm; the deposition stage is located in the ion chamber. The total height of the deposition stage is λ and it consists of a bottom column, a base platform, and a raised platform. For 2.45 GHz microwave, the diameter Ws of the bottom column is taken as 40 mm, the height Hs is taken as 100.45 mm, the diameter Wu of the base platform is taken as 120 mm, the height Hu is taken as 20 mm, the diameter Wp of the raised platform is taken as 80 mm, and the height Hp is taken as 2 mm; the coaxial antenna is connected to the coupling cavity, and the microwave coupling method is coaxial antenna coupling. The microwave mode is TEM. For 2.45 GHz microwave, the inner diameter R1 is taken as 20 mm, the outer diameter R2 is taken as 100 mm, the outer height H1 is taken as 0.5λ, that is, 61.23 mm, and the inner height H2 is taken as λ, that is, 122.45 mm.
[0037] As Figure 7 shown, under the conditions of 2.45 GHz, 2 kW, and 15 kPa, the maximum electron density is 3.77×10 17 / m 3 . If the electron density drops to of the maximum value is taken as the boundary of the discharge region, then the diameter of the discharge region is about 40.2 mm. As Figure 8 shown, under the conditions of 2.45 GHz, 2 kW, and 15 kPa, at steady state, the strong electric field is concentrated on the surface of the deposition stage, and the maximum value is 6.33×10 4 V / m.
[0038] On the premise of 2.45 GHz and 2 kW, the gas pressure in the ion chamber should be maintained at 15 - 17 kPa. When the gas pressure is lower than this range, the phenomenon of secondary plasma is likely to occur at the bottom of the quartz partition. As Figure 9As shown, when the pressure in the ion chamber is 13 kPa, secondary plasma is about to appear; when the pressure is higher than this range, the plasma discharge region shrinks significantly with the increase in pressure. As Figure 10 shown, when the pressure in the ion chamber is 21 kPa, the high electron density range shrinks significantly, and the discharge region is about 32.4 mm.
Claims
1. A low-power microwave cavity plasma reactor, characterized in that: The invention comprises a coaxial antenna (1), a coupling cavity (2), an ion chamber (3), a deposition platform (4), and a port (5) for applying coaxial TEM wave excitation; wherein the coupling cavity (2) and the ion chamber (3) form a total cavity, the total cavity is a cylindrical metal cavity, a quartz partition (6) is horizontally placed in the cavity, and the total cavity is divided into an upper coupling cavity (2) and a lower ion chamber (3), the deposition platform (4) is located in the ion chamber (3), the coaxial antenna (1) is located at the upper part of the coupling cavity (2), the port (5) for applying coaxial TEM wave excitation is located on the coaxial antenna (1), the microwave coupling mode is coaxial antenna coupling, and the microwave mode is TEM; the reactor is suitable for 915MHz and 2.45GHz microwaves.
2. The low-power microwave cavity plasma reactor according to claim 1, characterized in that: The total cavity diameter Wc is 2λ, and the height Hc is 3λ, where λ is the wavelength of the microwave.
3. The low-power microwave cavity plasma reactor according to claim 2, characterized in that: For 915MHz microwaves, Wc is 655.74mm and Hc is 983.61mm; for 2.45GHz microwaves, Wc is 244.90mm and Hc is 367.35mm.
4. The low-power microwave cavity plasma reactor according to claim 1, characterized in that: The thickness h of the quartz partition (6) is 7 mm, and the distance between the bottom of the quartz partition and the bottom of the total cavity Hg is 1.5λ.
5. The low-power microwave cavity plasma reactor according to claim 4, characterized in that: For 915MHz microwaves, Hg is 491.81mm; for 2.45GHz microwaves, Hg is 183.68mm.
6. The low-power microwave cavity plasma reactor according to claim 1, characterized in that: The deposition platform (4) has a total height of λ, and is composed of a bottom column (41), a base (42), and a raised platform (43); for 915MHz microwaves, the bottom column diameter Ws is 80mm, and the height Hs is 283.87mm; the base diameter Wu is 240mm, and the height Hu is 40mm; the raised platform diameter is 160mm, and the height is 4mm; for 2.45GHz microwaves, the bottom column diameter Ws is 40mm, and the height Hs is 100.45mm; the base diameter Wu is 120mm, and the height Hu is 20mm; the raised platform diameter Wp is 80mm, and the height Hp is 2mm.
7. The low-power microwave cavity plasma reactor according to claim 1, characterized in that: For the coaxial antenna (1), for 915 MHz microwaves, the inner diameter R1 is 40 mm, the outer diameter R2 is 200 mm, the outer height H1 is 0.5λ, i.e. 163.94 mm, and the inner height H2 is λ, i.e. 327.87 mm; for 2.45 GHz microwaves, the inner diameter R1 is 20 mm, the outer diameter R2 is 100 mm, the outer height H1 is 0.5λ, i.e. 61.23 mm, and the inner height H2 is λ, i.e. 122.45 mm.
8. The low-power microwave cavity plasma reactor according to claim 1, characterized in that: For the selected microwave excitation power, the reaction gas and reaction gas pressure in the ion chamber are set accordingly. The reaction gas can be hydrogen to excite and maintain hydrogen plasma, or hydrogen and methane can be used to achieve diamond film deposition.
9. The low-power microwave cavity plasma reactor according to claim 8, characterized in that: For 915MHz microwaves, the reaction gas is hydrogen, the power is 5kW, and the gas pressure in the ion chamber should be maintained at 8-10kPa; for 2.45GHz microwaves, the reaction gas is hydrogen, the power is 2kW, and the gas pressure in the ion chamber should be maintained at 15-17kPa.