Low-recombination-rate gas dissociation cavity structure

Abstract

The invention belongs to the technical field of remote plasma sources, and provides a low-recombination-rate gas dissociation cavity structure which comprises a gas inlet, a gas inlet end long cavity, a short cavity, a gas outlet end long cavity, a gas outlet, an ignition wire, a vacuum pump and a gas outlet gas pressure gauge, the upper end of the gas inlet end long cavity is connected with the gas inlet, and the gas inlet end long cavity is grounded; the upper end of the short cavity is connected with the lower end of the air inlet end long cavity; the upper end of the air outlet end long cavity is connected with the lower end of the short cavity, and the air outlet end long cavity is grounded; the air outlet is connected with the lower end of the air outlet end long cavity; the ignition wire is connected with the short cavity; a cavity inner diameter; and the length of the cavity and the diameter S of the air outlet are equal to L * (25-35%). The area of the gas outlet of the gas dissociation cavity is increased, the recombination rate of free radicals after gas dissociation is reduced, then active free radicals are efficiently generated, high reaction flux is provided for etching / deposition, and therefore the chip capacity and yield are improved.

Description

Technical Field

[0001] This invention relates to the field of remote plasma source technology, and more specifically to a low recombination rate gas dissociation cavity structure. Background Technology

[0002] Remote Plasma Sources (RPS) effectively prevent damage to sensitive devices from high-energy ions by physically separating the plasma generation and processing regions, while providing highly reactive free radicals and neutral particles. They are widely used in processes such as chip etching, surface cleaning, and thin film deposition. However, their design and operation still face some challenges, such as plasma uniformity, gas flow control, and control of gas recombination and dissociation rates.

[0003] Remote plasma sources primarily provide power through their power conversion system, achieving gas dissociation within a corrosion-resistant gas dissociation chamber. This chamber typically comprises an inlet chamber, an ionization chamber, an outlet chamber, and a return chamber. Gas enters the chamber through the inlet, undergoing ionization within the ionization chamber to generate plasma. To improve gas ionization efficiency and plasma stability, the chamber structure design must consider the uniformity of gas flow and the optimization of the electric field distribution. Furthermore, to reduce gas recombination and increase dissociation rate, the chamber structure design also requires appropriate dimensions for the inlet / outlet ports, the inner diameter of the chamber, and the length of the chamber.

[0004] Existing gas dissociation chamber designs suffer from uneven gas distribution, leading to low dissociation efficiency during gas flow and ionization, and hindering the efficient generation of free radicals. For example, turbulent and irregular flow can cause ionization instability, affecting plasma generation and reaction efficiency, thereby reducing chip yield.

[0005] From the perspective of structural complexity and durability, existing remote plasma source gas dissociation chambers are complex in structure and have numerous components. Taking the common aluminum chamber as an example, although the relatively hard aluminum material has a certain strength, the outer surface of the chamber is easily damaged, greatly reducing the service life of the chamber. Moreover, due to the complex structure, high-precision alignment is required during assembly to ensure airtightness, which undoubtedly increases time and labor costs. For example, in some remote plasma source devices in the semiconductor manufacturing field, the chamber is assembled from multiple parts, the assembly process is cumbersome, and even slight deviations can affect the overall performance. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a low recombination rate gas dissociation chamber structure to solve the problem that current gas dissociation chamber structures suffer from uneven gas distribution, resulting in low gas dissociation efficiency during gas flow and ionization, and thus failing to efficiently generate free radicals.

[0007] This invention provides a low recombination rate gas dissociation chamber structure, comprising:

[0008] Air intake;

[0009] The long cavity at the air inlet end is connected to the air inlet at its upper end, and the long cavity at the air inlet end is grounded;

[0010] The short cavity is connected at its upper end to the lower end of the long cavity at the air inlet end;

[0011] The long cavity at the air outlet is connected at its upper end to the lower end of the short cavity, and the long cavity at the air outlet is grounded.

[0012] The air outlet is connected to the lower end of the long cavity at the air outlet end;

[0013] The ignition wire is connected to the short cavity.

[0014] Cavity inner diameter ,

[0015] in, This is the Debye length coefficient. For the central electron density, The electron density at the wall surface;

[0016] cavity length ,

[0017] in, For airflow velocity, The surface recombination coefficient, The average velocity of gas molecules, The target composite rate;

[0018] The diameter of the air outlet is S = L × (25%~35%).

[0019] As can be seen from the above technical solutions, although large-size cavities can reduce wall recombination losses, they lead to a decrease in plasma density and a deterioration in uniformity; small-size cavities can increase density, but they increase the loss of active particles. This invention determines the inner diameter D of the cavity based on electron density constraints and the cavity length L based on minimizing recombination losses. By increasing the gas dissociation cavity outlet area, the recombination rate of free radicals after gas dissociation is reduced, thereby efficiently generating active free radicals, providing high reaction throughput for etching / deposition, and thus improving chip production capacity and yield.

[0020] Optionally, it also includes:

[0021] A vacuum pump, connected to the outlet, is used to extract gas from the cavity.

[0022] An outlet gas pressure gauge is used to monitor the outlet pressure; if the outlet pressure P is greater than the pressure threshold, the vacuum pump is controlled to increase the inlet pumping speed to reduce the outlet pressure.

[0023] As can be seen from the above technical solution, the present invention detects the pressure state of the outlet by an outlet gas pressure meter. If the pressure is greater than the pressure threshold, the pumping speed of the inlet is increased to reduce the pressure inside the cavity, thereby reducing the recombination rate of plasma at the outlet.

[0024] Optionally, the system also includes a gas distribution plate, the upper end of which is connected to the air inlet, and the lower end of which is connected to the long cavity at the air inlet. The gas distribution plate has vertical through holes and inclined through holes, with the inclined through holes located at both ends of the vertical through holes. The gas distribution plate is used to uniformly distribute the airflow within the plasma channel, improving plasma stability and creating rotating airflows in opposite directions in the two short cavities, so that they converge at the outlet for discharge.

[0025] Optionally, the inclined through holes are symmetrically arranged at both ends of the air distribution plate, and the angle between the inclined through holes and the horizontal plane is 40°.

[0026] Optionally, the short cavity is connected to the long cavity at the inlet and the long cavity at the outlet via a ceramic ring and a sealing ring. The ceramic ring and sealing ring ensure airtightness, have a simple structure, and prevent plasma or reactive gas leakage, thus avoiding disruption of the vacuum environment and impact on process stability.

[0027] By adopting the above technical solution, this application has the following beneficial effects:

[0028] This invention determines the inner diameter D of the cavity based on electron density constraints and the cavity length L based on minimizing recombination loss. By increasing the outlet area of ​​the gas dissociation cavity, the recombination rate of free radicals after gas dissociation is reduced, thereby efficiently generating active free radicals and providing high reaction throughput for etching / deposition, thus improving chip production capacity and yield.

[0029] This invention uses an outlet gas pressure gauge for coordinated pressure control, dynamically adjusts the vacuum pump speed, and monitors the outlet pressure. If the pressure exceeds a pressure threshold, the inlet pump speed S can be increased. p This reduces the internal pressure P and decreases the recombination rate of the gas at the outlet. Attached Figure Description

[0030] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0031] Figure 1 A schematic diagram of a low recombination rate gas dissociation chamber structure provided by an embodiment of the present invention is shown;

[0032] Figure 2 A cross-sectional view of a low recombination rate gas dissociation chamber structure provided in an embodiment of the present invention is shown;

[0033] Figure 3 for Figure 2 Dimensioning diagram;

[0034] Figure 4 One of the bottom views of the air distribution plate provided in an embodiment of the present invention is shown;

[0035] Figure 5 A second bottom view of the air distribution plate provided in an embodiment of the present invention is shown;

[0036] Figure 6 The third bottom view of the air distribution plate provided in the embodiment of the present invention is shown;

[0037] Figure 7 A schematic diagram of the short cavity provided in an embodiment of the present invention is shown;

[0038] Figure 8 This diagram illustrates the reaction equations for constructing a remote plasma source model using a two-dimensional model, as provided in an embodiment of the present invention.

[0039] Figure 9 One of the schematic diagrams of electron density distribution provided in the embodiments of the present invention is shown;

[0040] Figure 10 This is a second schematic diagram of the electron density distribution provided in an embodiment of the present invention;

[0041] Figure 11 The third schematic diagram of the electron density distribution provided in the embodiment of the present invention is shown.

[0042] Figure label:

[0043] 101 - Air inlet; 102 - Long cavity at the air inlet end; 103 - Short cavity; 104 - Long cavity at the air outlet end; 105 - Air outlet; 106 - Gas pressure gauge at the air outlet.

[0044] 201 - Air inlet channel; 202 - Long inlet channel; 203 - Short channel; 204 - Long outlet channel; 205 - Outlet channel; 206 - Outlet gas pressure detection point;

[0045] 300 - Air distribution plate; 301 - Vertical through hole; 302 - Inclined through hole;

[0046] 401 - Ceramic ring; 402 - Sealing ring; 403 - Sealing ring mounting groove. Detailed Implementation

[0047] The embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of the present invention and are therefore merely examples, and should not be construed as limiting the scope of protection of the present invention.

[0048] It should be noted that, unless otherwise stated, the technical or scientific terms used in this application should have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0049] In one embodiment, such as Figure 1 As shown, a low recombination rate gas dissociation chamber structure is provided, including an inlet 101, an inlet-end long cavity 102, a short cavity 103, an outlet-end long cavity 104, an outlet 105, an ignition wire, a vacuum pump, and an outlet gas pressure gauge 106. The upper end of the inlet-end long cavity 102 is connected to the inlet 101, and the inlet-end long cavity 102 is grounded; the upper end of the short cavity 103 is connected to the lower end of the inlet-end long cavity 102; the outlet... The upper end of the long cavity 104 is connected to the lower end of the short cavity 103, and the long cavity 104 at the gas outlet is grounded; the gas outlet 105 is connected to the lower end of the long cavity 104 at the gas outlet; the ignition wire is connected to the short cavity 103; the vacuum pump is connected to the gas outlet and is used to extract gas from the cavity; the gas pressure gauge 106 at the gas outlet is used to monitor the gas outlet pressure; if the gas outlet pressure P is greater than the pressure threshold, the vacuum pump is controlled to increase the pumping speed at the gas inlet to reduce the gas outlet pressure.

[0050] Pressure is controlled in a coordinated manner by the gas pressure gauge 106 at the outlet, and the pumping speed of the vacuum pump is dynamically adjusted. (where S) p (For pumping speed), monitor the outlet pressure; if it exceeds the pressure threshold, increase the inlet pumping speed S. p This reduces the internal pressure P and decreases the recombination rate of the gas at the outlet 105.

[0051] like Figure 2As shown, the cavity structure includes interconnected air chambers, which include an inlet air passage 201 located at the inlet 101, an inlet long cavity air passage 202 located at the inlet long cavity 102, a short cavity air passage 203 located at the short cavity, an outlet long cavity air passage 204 located at the outlet long cavity 104, and an outlet air passage 205 located at the outlet 105. The inlet air passage 201, the inlet long cavity air passage 202, the short cavity air passage 203, the outlet long cavity air passage 204, and the outlet air passage 205 are connected sequentially. The inlet air passage 201 and the outlet air passage 205 are also connected to the inlet 101 and the outlet 105, respectively. The outlet gas pressure detection point 206 is close to the outlet and is connected to a gas pressure detector 106 to regulate the gas pressure at the outlet 105.

[0052] like Figure 2 As shown, it also includes a gas distribution plate 300, the upper end of which is connected to the air inlet, and the lower end of which is connected to the long cavity 102 at the air inlet. The gas distribution plate 300 has a vertical through hole 301 and an inclined through hole 302, with the inclined through hole 302 located at both ends of the vertical through hole 301. The gas distribution plate 300 is used to uniformly distribute the airflow within the plasma channel, improving plasma stability and forming rotating airflows in opposite directions in the two short cavities 103, so that they can converge at the outlet and be discharged.

[0053] Inclined through holes 302 are symmetrically arranged at both ends of the air distribution plate 300, and the angle between the inclined through holes 302 and the horizontal plane is 40°. Figure 4-6 Three different configurations of vertical through holes 301 and / or inclined through holes 302 are shown, and specific configurations can be made according to actual conditions.

[0054] See Figure 7 The short cavity 103 is connected to the long cavity 102 at the inlet end and the long cavity 104 at the outlet end via a ceramic ring 401 and a sealing ring 402. The ceramic ring 401 and the sealing ring 402 achieve a seal to ensure airtightness. The structure is simple and can prevent leakage of plasma or reactive gases, thus avoiding damage to the vacuum environment and affecting process stability.

[0055] In one specific embodiment, a sealing ring mounting groove 403 is provided on the end face of the short cavity 103, and a sealing ring mounting groove 403 is also provided on the end faces of the long cavity 102 at the air inlet and the long cavity 104 at the air outlet. The upper and lower end faces of the short cavity 103 and the sealing ring mounting groove 403 are all subjected to hard anodizing treatment to prevent the sealing ring 402 from being corroded and affecting the airtightness of the cavity.

[0056] In one embodiment, such as Figure 3As shown, by adjusting the inner diameter D of the cavity, the cavity length L, and the outlet diameter S, the gas dissociation cavity outlet area is increased, the recombination rate of free radicals after gas dissociation is reduced, and thus active free radicals are generated efficiently, providing high reaction throughput for etching / deposition, thereby improving chip production capacity and yield.

[0057] Specifically, the inner diameter of the cavity ,

[0058] in, This is the Debye length coefficient. For the central electron density, The electron density at the wall surface;

[0059] cavity length ,

[0060] in, For airflow velocity, The surface recombination coefficient, The average velocity of gas molecules, The target composite rate.

[0061] Then, the outlet diameter S is determined based on the cavity length L. The outlet diameter S = L × (25%~35%).

[0062] While large-size cavities can reduce wall recombination losses, they lead to decreased plasma density and poorer uniformity. Small-size cavities, on the other hand, can increase density but increase the loss of active particles. This invention determines the inner diameter D of the cavity based on electron density constraints and the cavity length L based on minimizing recombination losses. By increasing the outlet area of ​​the gas dissociation cavity, the recombination rate of free radicals after gas dissociation is reduced, thereby efficiently generating active free radicals and providing high reaction throughput for etching / deposition, thus improving chip production capacity and yield.

[0063] The following simulation verifies the effects of the cavity inner diameter D, cavity length L, and outlet diameter S on the plasma by constructing a theoretical model of the plasma source:

[0064] Plasma theoretical calculations mainly involve electrostatic field equations, electron transport equations, and heavy matter transport equations. The electrostatic field equations are used to solve for the electric field generated by gas discharge and can be calculated using the Poisson equation.

[0065] ,

[0066] ,

[0067] Where E is the electric field and V is the electric potential. The charge density is calculated using the number densities of electrons and other charged particles.

[0068] ,

[0069] And the initial electron density needs to be given through initial conditions.

[0070] In the electron transport model, the migration of electron density and the change in electron energy density are determined by the following formula:

[0071] Electron density:

[0072] ,

[0073] ,

[0074] For electron density, For electron flux, For electron migration rate, The electron diffusion rate is given by the electron density equation, where the value of u is provided by the flow field. This electron density equation can be used to solve for the densities of electrons, ions, and neutral particles outside the background gas. In COMSOL simulations, ions and neutral particles are calculated using the heavy mass transport equation, not the aforementioned equation.

[0075] Electron energy density:

[0076] ,

[0077] ,

[0078] The variables in the equation are the same as those in the electron density equation. The subscripts represent energy. The electron energy equation is used to solve for electron energy, and it also requires the electron migration rate.

[0079] In COMSOL, substances other than electrons are solved using the heavy matter equation. Therefore, mass constraint needs to be selected in the matter options, and the following equation can be solved:

[0080] ,

[0081] ,

[0082] ,

[0083] ,

[0084] Density of mixture in formula From an ideal gas, The mass fraction of the substance is the variable to be solved, and the value of u is provided by the flow field. The calculation formula will change depending on the diffusion model chosen.

[0085] In physical field coupling, the plasma conductivity can be obtained by coupling a magnetic field and a plasma field, and can be determined by the following formula:

[0086] ,

[0087] A two-dimensional model was used to construct a remote plasma source model, and plasma simulation was performed by setting different external excitations. The constructed two-dimensional model structure (rectangular ring shape, ring shape), the reaction equations used, and the boundary conditions are as follows:

[0088] The reaction equation is as follows Figure 8 As shown. The simplest gas was selected for simulation to verify the model's correctness; argon was chosen due to its simple reaction and suitability for model building. Due to limitations of the magnetic field model and the use of a 400kHz frequency, coils could not be used to control the current in the model; only surface current density was used for magnetic field simulation. The current density used in the two-dimensional model was 360A / m, equivalent to 14A. The two-dimensional model primarily observed the influence of changes in the cavity structure and magnetic field structure on the plasma physical properties.

[0089] The simulation conditions were: current density of 360 A / m (equivalent to 14 A), frequency of 400 kHz, inlet mass flow rate of 100 sccm, and pressure of 1 torr. The default chamber inner diameter was set to 40 mm, the outlet diameter to 50 mm, and the inlet diameter to 50 mm.

[0090] In a remote plasma source, the effect of the outlet size on electron density, pressure, and gas recombination rate can be quantitatively described by the following physical formula:

[0091] 1. Relationship between outlet size and electron density

[0092] electron density With the cross-sectional area A of the air outlet s Relationship:

[0093] ,

[0094] in, For input power, The average electron energy, For the thermal motion velocity of electrons ( , (Electron temperature), outlet cross-sectional area A s The increase is due to the weakening of electron confinement and accelerated diffusion, leading to an increase in electron density. Increase;

[0095] 2. Relationship between air outlet size and pressure

[0096] Based on the law of conservation of mass and gas dynamics:

[0097] ,

[0098] in, Where A is the gas mass flow rate, T is the gas temperature, and A is the outlet cross-sectional area. s The increase in pressure leads to an increase in the gas escape rate and a decrease in the intracavity pressure P.

[0099] 3. Relationship between outlet size and recombination rate

[0100] Taking the introduction of hydrogen gas as an example, the remote plasma source decomposes the hydrogen gas into hydrogen atoms, which easily recombine into hydrogen gas at the outlet of the cavity; the surface recombination rate of H atoms is expressed as:

[0101] ,

[0102] in, For H atomic number density, The surface recombination coefficient, Let S be the average thermal velocity of H atoms, and S / V be the ratio of the internal surface area to the volume of the cavity; from the above formula, it can be seen that the outlet area A s As the volume increases, the equivalent S / V ratio of the cavity decreases, thus reducing the recombination rate. To minimize recombination losses, low S / V cavities should be designed; for example, elliptical cylindrical cavities are preferable to cuboid cavities.

[0103] 4. Relationship between outlet size and gas flow rate

[0104] The outlet size affects the gas velocity and outlet pressure; gas recombination losses only occur at the outlet end; according to the gas law, we can obtain:

[0105] ,

[0106] in, R is the gas mass flow rate. s Let A be the specific gas constant, T be the gas temperature, and A be the specific gas constant. s Where v is the cross-sectional area of ​​the outlet and v is the airflow velocity; in addition, pressure can be controlled in conjunction with the outlet pressure gauge to dynamically adjust the vacuum pump speed. (where S) p (For pumping speed), monitor the pressure at the outlet. If it exceeds the pressure threshold, increase the pumping speed at the outlet to reduce the pressure inside the cavity and reduce the recombination rate of gas at the outlet.

[0107] 1) The influence of air inlet and outlet

[0108] The external conditions used for the inlet and outlet positions remain 14A, 400kHz frequency, 1000sccm inlet mass flow rate, and 1tor pressure. The inlet and outlet positions are analyzed first, followed by their sizes. To accurately analyze the impact of the inlet and outlet on the dissociation rate, the cavity is treated while maintaining its internal diameter D unchanged.

[0109] a) Effect of changes in the position of air inlet and outlet

[0110] Without changing the internal diameter D of the cavity, changing the vertical position of the inlet and outlet of the cavity affects the electron density distribution as follows: Figure 9 As shown in Table 1, the data before and after the run is compared:

[0111] Table 1

[0112]

[0113] Under the condition that all variables are kept the same, only the position of the inlet and outlet is changed. As can be seen from Table 1, the electron density and average temperature do not change much, but the outlet temperature increases significantly. This is because the outlet is closer to the two magnetic cores, making it easier for the reactant gas to be transported. The plasma on both sides is concentrated in the center, resulting in a relatively high outlet temperature. It can be seen that changing the length of the inlet and outlet channels has a low impact on the electron density.

[0114] b) Effect of changes in the size of the air inlet and outlet

[0115] Changes in air inlet size can be categorized into changes in inlet size and changes in outlet size. For example, increasing the inlet diameter by 2cm while keeping the outlet unchanged, increasing the outlet diameter by 2cm while keeping the inlet unchanged, and increasing both the inlet and outlet diameters by 2cm, the following data can be obtained:

[0116] Table 2

[0117]

[0118] As can be observed from Table 2, increasing the diameter of either the inlet or outlet will increase the electron density. However, a larger outlet will lead to an increase in outlet temperature. Increasing the diameter of both the inlet and outlet will result in greater power deposition and stronger energy absorption by the plasma from the magnetic field. The increase in the size of the inlet and outlet will, to some extent, make the plasma reaction more complete.

[0119] Reducing the inlet and outlet diameters will increase electron density, average temperature, and power deposition. The following data can be obtained by reducing the inlet diameter by 2 cm while keeping the outlet diameter unchanged, reducing the outlet diameter by 2 cm while keeping the inlet diameter unchanged, and reducing both the inlet and outlet diameters by 2 cm:

[0120] Table 3

[0121]

[0122] Table 3 verifies that the individual effects of the inlet and outlet reduce electron density while the temperature remains almost constant. The outlet temperature also decreases as the outlet size decreases, while power deposition slightly increases. The simulations above do not cover the state where both the inlet and outlet sizes decrease; this would be a superposition of two states. To investigate whether there is a limit to increasing the outlet diameter S, we will explore this further, focusing on the state where both the inlet and outlet sizes increase simultaneously.

[0123] Table 4

[0124]

[0125] As shown in Table 4, increasing the outlet diameter S can increase the average electron density, but the increase is minimal. After the outlet diameter S reaches 0.07 m, the average temperature rises very slowly, and further increasing the diameter actually reduces the total power deposition of the particles. Meanwhile, the outlet temperature increases with the outlet diameter S. Reduced particle power deposition leads to lower average particle velocity and energy, which is detrimental to subsequent plasma reactions. Therefore, based on the design formula for the outlet diameter S and cavity length L, a diameter of approximately 0.07 m is considered optimal, with a diameter-to-cavity length ratio of 0.28. Thus, an outlet diameter S of 25%–35% of the cavity length L represents the optimal size for the cavity's inlet and outlet.

[0126] Figure 10 In this design, the inner diameter of the cavity is set to 50mm, the outlet diameter S is 160mm, and the inlet diameter is 60mm; it is evident that increasing the outlet diameter increases the outlet area A. s This increases electron density However, the air outlet area A s Excessive pressure can cause the plasma to extinguish, resulting in gas backflow.

[0127] 2) Influence of cavity size

[0128] While large-size cavities can reduce wall recombination losses, they lead to a decrease in plasma density and a deterioration in uniformity; while small-size cavities can increase density, they increase the loss of active particles.

[0129] The design formula for the cavity inner diameter D (short cavity inner diameter) is given based on electron density constraints:

[0130] ,

[0131] in, This is the Debye length coefficient. For the central electron density, The electron density at the wall surface;

[0132] Formula for designing cavity length L based on minimizing composite loss:

[0133] ,

[0134] in, For airflow velocity, The surface recombination coefficient, The average velocity of gas molecules, The target recombination rate; given the same area, increasing the internal diameter D of the cavity will affect various properties of the plasma. For example... Figure 11 As shown, the new cavity is reconstructed to have the same inner diameter D, and the external variables such as frequency, current, and gas flow rate are also the same. Furthermore, the conclusion in b) is verified to obtain the following data:

[0135] Table 5

[0136]

[0137] As shown in Table 5, the cavity length L is 0.2m. When the cavity inner diameter D is 0.05m, it accounts for 25% of the cavity length L; when the cavity inner diameter D is 0.06m, it accounts for 30% of the cavity length L; and when the cavity inner diameter D is 0.07m, it accounts for 35% of the cavity length L. In Table 5, the average plasma electron density generated by two cavities with the same cavity inner diameter D is similar, and the outlet temperature and cavity average temperature are similar, but the power deposition is much lower. It is speculated that this may be because the cavity loop is shorter, the plasma collision is weakened, and the energy absorption is lower. As for the proportion of the outlet, the plasma state is the same as in b), but because the plasma loop is shorter, the power deposition is also less, but the electron density increases relatively more, which is consistent with the conclusion in b). Combining Tables 4 and 5, it can be considered that the optimal conditions are achieved when the cavity inner diameter D is 0.05m, i.e., the proportion is 25%, and the outlet diameter S is 0.07m.

[0138] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A low recombination rate gas dissociation chamber structure, characterized in that, include: Air intake; The long cavity at the air inlet end is connected to the air inlet at its upper end, and the long cavity at the air inlet end is grounded; The short cavity is connected at its upper end to the lower end of the long cavity at the air inlet end; The long cavity at the air outlet is connected at its upper end to the lower end of the short cavity, and the long cavity at the air outlet is grounded. The air outlet is connected to the lower end of the long cavity at the air outlet end; The ignition wire is connected to the short cavity. Cavity inner diameter , in, This is the Debye length coefficient. For the central electron density, The electron density at the wall surface; cavity length , in, For airflow velocity, The surface recombination coefficient, The average velocity of gas molecules, The target composite rate; air outlet diameter S = L ×(25%~35%).

2. The low recombination rate gas dissociation chamber structure according to claim 1, characterized in that, Also includes: A vacuum pump, connected to the outlet, is used to extract gas from the cavity. An outlet gas pressure gauge is used to monitor the outlet pressure; if the outlet pressure... P If the pressure exceeds the pressure threshold, the vacuum pump is controlled to increase the inlet pumping speed to reduce the outlet pressure.

3. The low recombination rate gas dissociation chamber structure according to claim 1, characterized in that, It also includes an air distribution plate, the upper end of which is connected to the air inlet, and the lower end of which is connected to the long cavity of the air inlet; the air distribution plate is provided with a vertical through hole and an inclined through hole, and the inclined through hole is located at both ends of the vertical through hole.

4. The low recombination rate gas dissociation chamber structure according to claim 3, characterized in that, The inclined through holes are symmetrically arranged at both ends of the air distribution plate, and the angle between the inclined through holes and the horizontal plane is 40°.

5. The low recombination rate gas dissociation chamber structure according to claim 1, characterized in that, The short cavity is connected to the long cavity at the air inlet and the long cavity at the air outlet via a ceramic ring and a sealing ring.

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