A gas dissociation cavity discharge structure and ignition control method

Abstract

This invention belongs to the field of remote plasma source technology and provides a gas dissociation cavity discharge structure and ignition control method. The discharge structure includes: a cavity for dissociating process gas; metal meshes spaced apart and embedded in the cavity, with the metal meshes connected by conductive components; a shell fitted over the outside of the cavity; ports located at both ends of the cavity; a baffle between the ports and the shell; a sealing ring A between the baffle, ports, and the cavity; and electrode wires passing through the shell, cavity, and metal meshes for high-voltage ignition. This invention, by setting multiple layers of metal mesh, can broaden the range of values ​​for pd. During ignition, discharge occurs along the metal mesh at electrode distance d that approaches the lowest breakdown voltage, thereby reducing the breakdown voltage during remote plasma source ignition and improving the ignition success rate of the remote plasma source.

Description

Technical Field

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

[0002] Remote plasma sources effectively prevent damage to sensitive devices from high-energy ions by physically separating the plasma generation and processing zones, 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 and ignition success rate. Furthermore, traditional plasma generators often use straight-pipe gas paths, where large amounts of high-energy electron and ion flows directly bombard the metal connectors at the inlet / outlet, generating metal particles that mix with the plasma. These metal particles travel with the plasma to the substrate surface, causing film contamination over time. Currently, some multi-segment cavity structures made of metal are prone to leakage at assembly interfaces, affecting product cleanliness. Additionally, the metal material is easily worn, which also hinders production yield.

[0003] Existing cavity structure designs typically use a fixed ignition voltage during the ignition process. When the gas type or gas pressure changes, the ignition breakdown voltage will also change. If the breakdown voltage needs to be increased, the originally set fixed ignition voltage will not be sufficient, leading to ignition failure and affecting the ignition success rate of remote plasma sources.

[0004] From the perspective of structural complexity and durability, existing remote plasma source dissociation cavities are complex in structure and have numerous components. Taking the common aluminum cavity as an example, although the relatively hard aluminum material has a certain strength, the outer surface of the cavity is easily damaged, greatly reducing the service life of the cavity. 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 cavity is assembled from multiple parts, the assembly process is cumbersome, and even slight deviations can affect the overall performance. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a gas dissociation cavity discharge structure and ignition control method to solve the problem that current cavity structures with fixed ignition voltages are prone to ignition failure when the gas type or pressure changes.

[0006] In a first aspect, the present invention provides a gas dissociation cavity discharge structure, comprising:

[0007] The cavity is used to dissociate process gases;

[0008] Metal meshes are arranged concentrically and embedded in the cavity; the metal meshes are connected by conductive components, and the diameter and length of the metal meshes gradually increase from the inside to the outside.

[0009] A housing, fitted over the outside of the cavity;

[0010] Ports are located at both ends of the cavity, and are used for air inlet and outlet of the cavity, respectively. The ports are grounded.

[0011] A baffle is disposed between the port and the housing;

[0012] A sealing ring A is disposed between the baffle, the port, and the cavity;

[0013] Electrode wires pass through the housing, the cavity, and the metal mesh to conduct electricity for high-voltage ignition.

[0014] As can be seen from the above technical solution, the gas dissociation cavity discharge structure provided by the present invention can broaden the range of pd values ​​by setting up a multi-layer metal mesh. During ignition, the discharge is carried out along the electrode distance d corresponding to the lowest breakdown voltage at this time, thereby reducing the breakdown voltage during remote plasma source ignition and improving the ignition success rate of remote plasma source. The cavity structure is simple and easy to assemble.

[0015] Optionally, the housing and the port are provided with mounting grooves opposite each other, and a sealing ring B is disposed in the mounting groove, with the baffle disposed between the sealing rings B. By setting the sealing rings B, they can work in conjunction with the sealing ring A to ensure the sealing effect of the cavity, prevent plasma or reactive gas leakage, avoid damage to the vacuum environment, and prevent affecting process stability.

[0016] Optionally, the electrode wire is located on the horizontal plane of symmetry of the metal mesh.

[0017] Optionally, the innermost metal mesh is integrally connected from top to bottom, and the metal meshes located on the outer side of the innermost layer each have an upper metal mesh and a lower metal mesh, which are spaced apart.

[0018] Optionally, the metal mesh has three layers, and the electrode distance is... d i The vertical distance from the end of the metal mesh to the port.

[0019] Optionally, the metal mesh is made of a metal material with a melting point of 1000-3000℃.

[0020] In a second aspect, the present invention provides an ignition control method for igniting a gas dissociation cavity discharge structure of any possible implementation of the first aspect, comprising:

[0021] S1. Establishment based on different process gases pd Minimize the database; pd Gas pressure p and electrode distance d The product;

[0022] S2. Based on the electrode distance of the metal mesh d i Calculate different gas pressures p The required value range; electrode distance d i This is the vertical distance from the end of the metal mesh to the port. i The quantity of metal mesh;

[0023] S3. Select the appropriate gas pressure p During remote plasma source ignition, the multi-layered metal mesh enables... pd Approaching .

[0024] As can be seen from the above technical solution, the ignition control method provided by the present invention can control different process gases with different properties. The gas dissociation cavity discharge structure, based on a multi-layer metal mesh, can provide different electrode distances, thereby broadening the range of pd values. Under varying gas pressure conditions, different gas pressures can be provided. p Messenger pd Approaching This achieves optimal balance and reduces the breakdown voltage during remote plasma source ignition.

[0025] By adopting the above technical solution, this application has the following beneficial effects:

[0026] The present invention provides a gas dissociation cavity discharge structure, which can broaden the range of values ​​of pd by setting up a multi-layer metal mesh. Specifically, according to Pascal's law, it can reduce the breakdown voltage when the remote plasma source is ignited. During ignition, the discharge is carried out along the electrode distance d corresponding to the minimum breakdown voltage at this time, thereby reducing the breakdown voltage when the remote plasma source is ignited and improving the ignition success rate of the remote plasma source.

[0027] The ignition control method provided by this invention addresses the different process gases. The gas dissociation cavity discharge structure, based on a multi-layer metal mesh, can provide different electrode distances, thereby broadening the range of values ​​for pd. Under varying gas pressure conditions, pd can be made to approach the desired value by providing different gas pressures p. This achieves optimal balance and reduces the breakdown voltage during remote plasma source ignition. Attached Figure Description

[0028] 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.

[0029] Figure 1 A schematic diagram of a gas dissociation cavity discharge structure provided in an embodiment of the present invention is shown;

[0030] Figure 2 It shows Figure 1 An explosion diagram;

[0031] Figure 3 Another schematic diagram of a gas dissociation cavity discharge structure provided in an embodiment of the present invention is shown;

[0032] Figure 4 It shows Figure 3 A cross-sectional view along the AA direction;

[0033] Figure 5 It shows Figure 4 Dimensioning diagram;

[0034] Figure 6 It shows Figure 5 Enlarged view of part B in the middle;

[0035] Figure 7 A schematic diagram of the metal mesh provided by the present invention is shown;

[0036] Figure 8 A partially enlarged view of the metal mesh provided by the present invention is shown;

[0037] Figure 9 The effect of gas pressure p and electrode distance d on breakdown voltage for different gases is shown. A diagram illustrating the impact;

[0038] Figure 10 A flowchart of the ignition control method provided by the present invention is shown.

[0039] Figure label:

[0040] 100-Cavity; 200-Metal mesh; 300-Shell; 400-Port; 500-Baffle; 601-Sealing ring A; 602-Sealing ring B; 700-Electrode wire; 800-Copper paste point. Detailed Implementation

[0041] 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.

[0042] 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.

[0043] In one embodiment, such as Figure 1-5 As shown, a gas dissociation cavity discharge structure is provided, comprising:

[0044] Chamber 100 is used for dissociating process gases;

[0045] Metal mesh 200 is spaced apart and embedded in cavity 100; the metal mesh 200 is connected to each other through conductive components, and the diameter D and length S of the metal mesh 200 gradually increase from the inside to the outside.

[0046] The housing 300 is fitted onto the outside of the cavity 100;

[0047] Port 400 is located at both ends of cavity 100 and is used for air inlet and outlet of cavity 100 respectively. Port 400 is grounded.

[0048] A baffle 500 is disposed between port 400 and housing 300;

[0049] A sealing ring A601 is disposed between baffle 500, port 400 and cavity 100;

[0050] The electrode wire 700 passes through the housing 300, cavity 100 and metal mesh 200 for high-voltage ignition; the electrode wire 700 is located on the horizontal symmetry plane of the metal mesh 200.

[0051] This embodiment can be widened by setting multiple layers of metal mesh 200. pd The value range is determined by the electrode distance at which the voltage approaches the minimum breakdown voltage during ignition. d The metal mesh 200 is discharged, thereby reducing the breakdown voltage during remote plasma source ignition and improving the ignition success rate of the remote plasma source.

[0052] Specifically, there is a 1.16mm gap 900 between port 400 and cavity 100.

[0053] The housing 300 and port 400 are provided with mounting grooves opposite each other. A sealing ring B602 is installed in the mounting groove, and a baffle 500 is disposed between the sealing rings B602. By setting the sealing rings B602, they can work with the sealing rings A601 to ensure the sealing effect of the cavity 100, prevent the leakage of plasma or reactive gases, avoid damage to the vacuum environment, and prevent affecting the stability of the process.

[0054] like Figure 4-6 As shown, the innermost metal mesh 200 is integrally connected from top to bottom, and the outermost metal meshes 200 all have upper and lower metal meshes, which are spaced apart. By keeping the innermost metal mesh as a whole, while the remaining metal meshes only have upper and lower metal meshes, costs can be saved.

[0055] In one specific embodiment, the lengths of the upper and lower metal meshes are 2.64 mm.

[0056] In one specific embodiment, the cavity 100 is made of silicon nitride, the housing 300, the port 400 and the baffle 500 are made of aluminum, and the metal mesh is made of copper.

[0057] Metal mesh Figure 7-8 As shown, the multiple layers of metal mesh are connected by conductive elements. Specifically, due to the very small spacing between the metal meshes, the conductive elements are copper paste dots. For example, in one specific design, the spacing between the inner, middle, and outer metal mesh layers is 0.18 mm, allowing direct connection between the metal meshes via copper paste dots. Figure 8 The location indicated by the middle arrow is where the copper paste dots are set. The number of copper paste dots is determined by the required ignition area and they should be evenly distributed; those skilled in the art can make specific settings according to actual needs, which will not be elaborated in this embodiment.

[0058] In one specific embodiment, the inner metal mesh has 24 copper paste dots, which are spaced apart from each other; and the copper paste dots between different metal mesh layers are also evenly spaced.

[0059] During remote plasma ignition, when the gas is not ionized, the system is approximately open-circuited and exhibits high impedance, requiring a sufficient breakdown voltage to trigger ionization. Breakdown voltage The Pascal's Law describes it as follows:

[0060] (1)

[0061] p This refers to gas pressure; d Where A is the electrode distance; A and B are constants related to the type of gas (e.g., for argon: A≈13.6cm). −1 Torr −1 B≈176V·cm −1Torr −1 ); This represents the secondary electron emission coefficient.

[0062] At this point, the load impedance is extremely high, approximating an open circuit:

[0063] (2)

[0064] The voltage needs to reach Only when the breakdown condition is met can discharge be triggered. Impedance and voltage are not directly proportional.

[0065] According to Pascal's Law (1), the breakdown voltage does not change with the electrode distance. d It doesn't change linearly, but rather has a minimum value. When d When the voltage is very low, a very high voltage is required for breakdown because the electrons have to travel a short distance and there aren't enough collisions. However, if... d If the voltage is too high, although the energy of a single collision is high, the number of collisions decreases, and a higher voltage is still needed to maintain sufficient ionization. Therefore, there exists a certain... d The value corresponds to the lowest breakdown voltage;

[0066] Figure 9 The gas pressure is shown for different gases. p and electrode distance d For breakdown voltage Effect; for any given gas, there exists a specific ( pd ) best Value, making the breakdown voltage Reaching the minimum value corresponds to the minimum breakdown voltage. It depends on the type of gas.

[0067] At constant air pressure p Below, electrode distance d Changes in breakdown voltage The impact is as follows:

[0068] when d Very small, that is At this point, the path of the electron towards the anode is very short, and the kinetic energy gained by the electron between two collisions is insufficient to ionize the gas molecules, thus requiring a higher breakdown voltage. This provides a stronger electric field, allowing electrons to gain sufficient kinetic energy for ionization over a shorter distance.

[0069] when d Gradually increase, that is Approaching At this point, electrons have sufficient distance to accelerate in the electric field, thus gaining kinetic energy exceeding their ionization energy before the collision. Simultaneously, the path length ensures a sufficient number of collisions to trigger avalanche breakdown. This achieves optimal equilibrium, at which point the minimum breakdown voltage is required. .

[0070] when d Very large, that is At high energy levels, electrons can gain very high kinetic energy between collisions, far exceeding their ionization energy, but the number of collisions is relatively reduced. More importantly, when high-energy electrons collide with molecules, the proportion of excitation rather than ionization increases, resulting in a phenomenon where the excitation cross-section is larger than the ionization cross-section or energy is lost due to elastic collisions. To compensate for the decrease in ionization efficiency caused by the reduced number of collisions and the increase in ineffective collisions, a higher voltage is required. To maintain the ionization rate required for the avalanche process.

[0071] See Figure 5 The distance between the innermost layer of the three-layer (or more) metal mesh and the aluminum baffle The thickness is 9.25mm, the distance from the inner mesh to the inner wall is 0.35mm, and the middle layer of the metal mesh... The distance between the outer layer of the metal mesh and the aluminum baffle is 7.43mm. The distance is 5.76 mm, of which the spacing between the inner, middle, and outer metal mesh layers is 0.18 mm, and the distance between the horizontal axis of symmetry of the metal mesh and the aluminum baffle is 28.66 mm. Therefore, the maximum value of the electrode distance d is... l , l =28.66mm.

[0072] In one embodiment, an ignition control method is provided, which controls ignition when the gas pressure changes, such as Figure 10 As shown, it includes:

[0073] S1. First, using the Pascal formula (1), establish a system based on different process gases. pd Minimize the database. For example... Figure 6 As shown, due to the minimum breakdown voltage required for different process gases corresponding pd Unlike others, it obtains the minimum breakdown voltage in advance. corresponding pd This facilitates the selection of a suitable gas pressure under a fixed electrode spacing. p This leads to the lowest breakdown voltage. .

[0074] S2. Based on the electrode distance of the metal mesh d i Calculate different gas pressures p The required value range.

[0075] Electrode distance provided for a specific embodiment of the gas dissociation cavity discharge structure d 1. d 2 and d The diameters are 9.25 mm, 7.43 mm, and 5.76 mm, respectively, and the typical gas pressure range is 0.15~3 Torr. pd The range is shown in Table 1.

[0076] Table 1

[0077]

[0078] Table 1 shows the corresponding values ​​for different gas pressures and different electrode distances. pd Range. In applications, different gas pressures... p The value range is generally between 0.15 and 3 Torr. For the same cavity, the electrode distance... d i fixed, pd (Gas pressure) p and electrode distance d The product of these two factors (T and M) ranges from 0.864 to 85.98 Torr·mm, corresponding to... Figure 9 It is evident that this meets the minimum ignition voltage requirements for most gases.

[0079] S3. Select the appropriate gas pressure p During remote plasma source ignition, the multi-layered metal mesh structure enables... pd Approaching Therefore, breakdown voltage It is also close to the minimum breakdown voltage. It is easier to ignite successfully.

[0080] Under constant pressure control, the structure of multi-layer metal mesh can be broadened. pd The range of values ​​for this value is used to reduce the breakdown voltage during remote plasma source ignition. At the moment of ignition, the minimum breakdown voltage is met. Corresponding electrode distance The metal mesh discharges. For example, by introducing helium gas, such as... Figure 9 As shown, the helium gas at this time corresponds to Around 3.2 Torr·cm, taking the gas pressure as 3 Torr, then, pd The values ​​for the outer, middle, and inner layers were 1.728, 2.229, and 2.775 Torr·cm, respectively. Since... pd A value of 2.775 is closer to... Therefore, when the remote plasma source is ignited, the discharge process is as follows: high voltage is supplied to the multi-layer metal mesh through the electrode wire, and the inner layer metal mesh connected to it breaks through the cavity with a layer thickness of 0.35mm and flows into the port along the inner wall of the cavity. At this time, the plasma dissociates and acts as a wire.

[0081] 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 gas dissociation chamber discharge structure, characterized by, It comprises: a cavity for dissociating process gas; a plurality of concentrically spaced metal nets embedded in the cavity; the metal nets are connected by conductive elements; the diameter and length of the metal nets gradually increase from the innermost layer to the outermost layer; a shell covering the outside of the cavity; ports at both ends of the cavity for the inlet and outlet of the process gas, the ports being grounded; a baffle between the ports and the shell; a sealing ring A between the baffle, the ports and the cavity; an electrode lead wire passing through the shell, the cavity and the metal nets for high-voltage ignition.

2. The gas dissociation chamber discharge structure of claim 1, wherein, The shell and the ports are oppositely provided with mounting grooves, the mounting grooves are provided with sealing rings B, and the baffle is arranged between the sealing rings B.

3. The gas dissociation chamber discharge structure of claim 2, wherein, The electrode lead wire is located at the horizontal symmetry plane of the metal nets.

4. The gas dissociation chamber discharge structure of claim 3, wherein, The innermost metal net is integrally connected from top to bottom, and the metal nets outside the innermost layer are upper metal nets and lower metal nets, which are arranged in intervals.

5. The gas dissociation chamber discharge structure of claim 4, wherein, The number of metal mesh is three layers, electrode distance d i is the vertical distance from the end of the metal mesh to the port.

6. The gas dissociation chamber discharge structure of claim 1, wherein, The material of the metal nets is a metal material with a melting point of 1000-3000℃.

7. A method of ignition control, characterized by, A device for igniting the gas dissociation cavity discharge structure according to any one of claims 1-6, comprising: S1. Establishing a minimum database for different process gases pd pd The product of the gas pressure p and the electrode distance d is minimized.​ S2. The electrode distance of the metal mesh is determined according to the metal mesh d i , the range of the demand value of different gas pressure p is calculated; the electrode distance is the vertical distance from the end of the metal mesh to the port, i is the number of metal meshes; S3. Selecting the appropriate gas pressure p The metal mesh structure allows for pd approaching the ignition of the remote plasma source.

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